Image processing device, display system, and electronic device

ABSTRACT

A display system including a display device and an image processing device is provided. The display device includes a second display panel overlapping with a first display panel on the display surface side. The second display panel has a region that transmits visible light adjacent to a display region. The region that transmits visible light of the second display panel overlaps with a display region of the first display panel, which makes a non-display region between display regions of two display panels in the display device small. The image processing device has a function of correcting the gray scale, which is included in image data, corresponding to at least one of a portion overlapping with the region that transmits visible light and a portion not overlapping with the region in the display region of the first display panel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/945,688, filed Nov. 19, 2015, now allowed, which claims the benefitof a foreign priority application filed in Japan as Serial No.2014-241476 on Nov. 28, 2014, both of which are incorporated byreference.

TECHNICAL FIELD

One embodiment of the present invention relates to an image processingdevice, a display system, and an electronic device.

Note that one embodiment of the present invention is not limited to theabove technical field. Examples of the technical field of one embodimentof the present invention include a semiconductor device, a displaydevice, a light-emitting device, a power storage device, a memorydevice, an electronic device, a lighting device, an input device (e.g.,a touch sensor), an input-output device (e.g., a touch panel), a drivingmethod thereof, and a manufacturing method thereof.

BACKGROUND ART

In recent years, larger display devices have been required. Largedisplay devices can be used for a television device for home use (alsoreferred to as a TV or a television receiver), digital signage, and apublic information display (PID), for example. A larger display regionof a display device can provide more information at a time. In addition,a larger display region attracts more attention, so that theeffectiveness of the advertisement is expected to be increased, forexample.

Larger display devices have been also required for application to mobiledevices. It has been considered to improve browsability by increasingthe area of a display region of the display device to increase theamount of information to be displayed at a time.

Light-emitting elements utilizing electroluminescence (also referred toas EL elements) have features such as ease of thinning and lightening,high-speed response to an input signal, and driving with adirect-current low voltage source; thus, application of the EL elementsto display devices has been proposed. For example, Patent Document 1discloses an example of a display device including an organic ELelement.

Patent Document 2 discloses a flexible active matrix light-emittingdevice in which an organic EL element and a transistor serving as aswitching element are provided over a film substrate.

REFERENCE Patent Document

[Patent Document 1] Japanese Published Patent Application No.2002-324673

[Patent Document 2] Japanese Published Patent Application No.2003-174153

DISCLOSURE OF INVENTION

An object of one embodiment of the present invention is to increase thesize of a display device. Another object of one embodiment of thepresent invention is to suppress display unevenness or luminanceunevenness of a display device. Another object of one embodiment of thepresent invention is to reduce the thickness or weight of a displaydevice. Another object of one embodiment of the present invention is toprovide a display device capable of displaying an image along a curvedsurface. Another object of one embodiment of the present invention is toprovide a highly browsable display device. Another object of oneembodiment of the present invention is to provide a display deviceincluding a wide display region in which a joint is hardly recognized.

Another object of one embodiment of the present invention is to providea novel image processing device, a novel display system, a novelelectronic device, or the like. Another object of one embodiment of thepresent invention is to provide an image processing device in which ajoint in a display region composed of a plurality of display panels ishardly recognized.

Note that the descriptions of these objects do not preclude theexistence of other objects. In one embodiment of the present invention,there is no need to achieve all the objects. Other objects can bederived from the description of the specification, the drawings, and theclaims.

One embodiment of the present invention is an image processing devicefor supplying an image signal to a display device. The image processingdevice includes an arithmetic portion. A first image signal andcorrection data are supplied to the arithmetic portion. The arithmeticportion has a function of correcting the first image signal on the basisof the correction data to produce a second image signal and a functionof supplying the second image signal to the display device. The displaydevice includes a first display panel and a second display panel. Thefirst display panel includes a first region having a function ofdisplaying an image. The second display panel includes a second regionand a third region. The second region has a function of displaying animage. The third region is adjacent to the second region. The thirdregion has a function of transmitting visible light. The first regionincludes a first portion overlapping with the third region on a displaysurface side. The second image signal is a signal in which gray scalecorresponding to the first portion is corrected.

One embodiment of the present invention is an image processing devicefor supplying an image signal to a display device. The image processingdevice includes an arithmetic portion. A first image signal andcorrection data are supplied to the arithmetic portion. The arithmeticportion has a function of correcting the first image signal on the basisof the correction data to produce a second image signal and a functionof supplying the second image signal to the display device. The displaydevice includes a first display panel and a second display panel. Thefirst display panel includes a first region having a function ofdisplaying an image. The second display panel includes a second regionand a third region. The second region has a function of displaying animage. The third region is adjacent to the second region. The thirdregion has a function of transmitting visible light. The first regionincludes a first portion overlapping with the third region on a displaysurface side. The second image signal is a signal in which gray scalecorresponding to at least part of the first region excluding the firstportion or at least part of the second region is corrected.

One embodiment of the present invention is a display system including adisplay device and an image processing device. The display deviceincludes a first display panel and a second display panel. The firstdisplay panel includes a first region having a function of displaying animage. The second display panel includes a second region and a thirdregion. The second region has a function of displaying an image. Thethird region is adjacent to the second region. The third region has afunction of transmitting visible light. The first region includes afirst portion overlapping with the third region on a display surfaceside. The image processing device includes an arithmetic portion. Afirst image signal and correction data are supplied to the arithmeticportion. The arithmetic portion has a function of correcting the firstimage signal on the basis of the correction data to produce a secondimage signal and a function of supplying the second image signal to thedisplay device. The second image signal is a signal in which gray scalecorresponding to the first portion is corrected.

One embodiment of the present invention is a display system including adisplay device and an image processing device. The display deviceincludes a first display panel and a second display panel. The firstdisplay panel includes a first region having a function of displaying animage. The second display panel includes a second region and a thirdregion. The second region has a function of displaying an image. Thethird region is adjacent to the second region. The third region has afunction of transmitting visible light. The first region includes afirst portion overlapping with the third region on a display surfaceside. The image processing device includes an arithmetic portion. Afirst image signal and correction data are supplied to the arithmeticportion. The arithmetic portion has a function of correcting the firstimage signal on the basis of the correction data to produce a secondimage signal and a function of supplying the second image signal to thedisplay device. The second image signal is a signal in which gray scalecorresponding to at least part of the first region excluding the firstportion or at least part of the second region is corrected.

The display system includes a detection device. The detection device mayhave a function of acquiring luminance data of the display device and afunction of supplying the luminance data to the image processing device.

The display device included in the display system may include alight-transmitting layer. The light-transmitting layer preferably has alight transmittance of higher than or equal to 80% on average at awavelength longer than or equal to 450 nm and shorter than or equal to700 nm, and has a higher refractive index than the air. Thelight-transmitting layer is between the first display panel and thesecond display panel. In addition, the light-transmitting layer is onthe display surface side of the first display panel and on the oppositeside of a display surface of the second display panel. The first portionhas a portion where the first region overlaps with the third region withthe light-transmitting layer positioned therebetween.

The display device included in the display system may be flexible. Atleast one of the display panels included in the display device may beflexible, or all display panels may be flexible, for example.

The image processing device includes a memory portion. The correctiondata is supplied to the memory portion. The memory portion preferablyhas a function of supplying the correction data to the arithmeticportion.

The second image signal may be subjected to gamma correction.

One embodiment of the present invention also includes an electronicdevice or a lighting device including the display system having any ofthe above structures. For example, one embodiment of the presentinvention is an electronic device including the display system havingany of the above structures, and an antenna, a battery, a housing, aspeaker, a microphone, an operation switch, or an operation button.

One embodiment of the present invention can increase the size of adisplay device. One embodiment of the present invention can suppressdisplay unevenness or luminance unevenness of a display device. Oneembodiment of the present invention can reduce the thickness or weightof a display device. One embodiment of the present invention can providea display device capable of displaying an image along a curved surface.One embodiment of the present invention can provide a highly browsabledisplay device. One embodiment of the present invention can provide adisplay device including a wide display region in which a joint ishardly recognized.

One embodiment of the present invention can provide a novel imageprocessing device, a novel display system, a novel electronic device, orthe like. One embodiment of the present invention can provide an imageprocessing device in which a joint in a display region composed of aplurality of display panels is hardly recognized.

Note that the description of these effects does not preclude theexistence of other effects. One embodiment of the present invention doesnot necessarily have all the effects listed above. Other effects can bederived from the description of the specification, the drawings, and theclaims.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1D illustrate examples of a display system and an imageprocessing device.

FIG. 2 illustrates an example of a display system.

FIG. 3 illustrates an example of a display system.

FIG. 4 illustrates an example of a display system.

FIGS. 5A to 5F each show a relationship between an input value and anoutput value.

FIGS. 6A and 6B illustrate examples of a display panel and a displaydevice.

FIGS. 7A to 7D each illustrate an example of pattern data.

FIGS. 8A and 8B each illustrate an example of a display device.

FIGS. 9A to 9C illustrate examples of a display device.

FIGS. 10A to 10D each illustrate an example of a display panel.

FIGS. 11A to 11C each illustrate an example of a display device.

FIGS. 12A to 12E each illustrate an example of a display device.

FIGS. 13A to 13F each illustrate an example of a display device.

FIGS. 14A to 14C illustrate examples of a display panel.

FIGS. 15A to 15C illustrate an example of a display panel.

FIGS. 16A to 16C each illustrate an example of a display device.

FIGS. 17A to 17C illustrate examples of a light-emitting panel.

FIG. 18 illustrates an example of a display device.

FIGS. 19A to 19C each illustrate an example of a light-emitting panel.

FIGS. 20A and 20B each illustrate an example of a light-emitting panel.

FIGS. 21A to 21C illustrate an example of a touch panel.

FIGS. 22A and 22B illustrate an example of a touch panel.

FIGS. 23A to 23C each illustrate an example of a touch panel.

FIGS. 24A to 24C each illustrate an example of a touch panel.

FIG. 25 illustrates an example of a touch panel.

FIG. 26 illustrates an example of a touch panel.

FIGS. 27A to 27F illustrate examples of electronic devices and lightingdevices.

FIGS. 28A1, 28A2, and 28B to 28I illustrate examples of electronicdevices.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments will be described in detail with reference to drawings. Notethat the present invention is not limited to the description below, andit is easily understood by those skilled in the art that various changesand modifications can be made without departing from the spirit andscope of the present invention. Accordingly, the present inventionshould not be interpreted as being limited to the content of theembodiments below.

Note that in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and description of suchportions is not repeated. Furthermore, the same hatching pattern isapplied to portions having similar functions, and the portions are notdenoted by particular reference numerals in some cases.

In addition, the position, size, range, or the like of each structureillustrated in drawings is not accurately represented in some cases foreasy understanding. Therefore, the disclosed invention is notnecessarily limited to the position, the size, the range, or the likedisclosed in the drawings.

Note that the terms “film” and “layer” can be interchanged with eachother depending on the case or circumstances. For example, the term“conductive layer” can be changed into the term “conductive film” insome cases, and the term “insulating film” can be changed into the term“insulating layer” in some cases.

Note that in this specification, examples of the case where X and Y areelectrically connected include the case where X and Y are directlyconnected without another element interposed therebetween and the casewhere one or more elements that enable electrical connection between Xand Y (e.g., a switch, a transistor, a capacitor, an inductor, aresistor, a diode, a display element, a light-emitting element, or aload) are connected between X and Y. A switch is controlled to be on oroff. That is, a switch is conducting or not conducting (is turned on oroff) to determine whether current flows therethrough or not.Alternatively, the switch has a function of selecting and changing acurrent path.

Embodiment 1

In this embodiment, an image processing device of one embodiment of thepresent invention and a display system of one embodiment of the presentinvention will be described with reference to drawings.

When a plurality of display panels are arranged in one or moredirections (e.g., in one column or in matrix), a display device with alarge display region can be manufactured.

In the case where a large display device is manufactured using aplurality of display panels, each of the display panels is not requiredto be large. Thus, an apparatus for manufacturing the display panel doesnot need to be increased in size, whereby space-saving can be achieved.Furthermore, since an apparatus for manufacturing small- andmedium-sized display panels can be used and a novel apparatus formanufacturing large display devices is unnecessary, manufacturing costcan be reduced. In addition, a decrease in yield caused by an increasein the size of a display panel can be suppressed.

A display device including a plurality of display panels has a largerdisplay region than a display device including one display panel whenthe display panels have the same size, and has an effect of displayingmore information at a time, for example.

However, in the case where output images of the plurality of displaypanels are displayed as one image, a user of the display device sees theimage as divided because each of the display panels has a non-displayregion that surrounds a display region.

Making the non-display regions of the display panels small (usingdisplay panels with narrow frames) can prevent an image on the displaypanels from appearing divided; however, it is difficult to totallyremove the non-display region of the display panel.

A small non-display region of the display panel leads to a decrease inthe distance between an edge of the display panel and an element in thedisplay panel, in which case the element easily deteriorates byimpurities entering from outside the display panel in some cases.

Thus, in one embodiment of the present invention, a plurality of displaypanels are arranged to partly overlap with one another. In two displaypanels overlapping with each other, at least a display panel positionedon the display surface side (upper side) includes a region thattransmits visible light and a display region adjacent to each other. Inone embodiment of the present invention, a display region of a displaypanel positioned on a lower side and the region that transmits visiblelight of the display panel on the upper side overlap with each other.Thus, a non-display region that appears between the display regions ofthe two display panels overlapping with each other can be reduced oreven removed. Accordingly, a large display device in which a jointbetween display panels is hardly recognized by a user can be obtained.

At least part of a non-display region of the display panel on the upperside transmits visible light, and can overlap with the display region ofthe display panel on the lower side. Furthermore, at least part of anon-display region of the display panel on the lower side can overlapwith the display region of the display panel on the upper side or aregion that blocks visible light thereof. It is not necessary to reducethe areas of the non-display regions because a reduction in the area ofthe frame of the display device (a reduction in area except a displayregion) is not affected by these regions.

A large non-display region of the display panel leads to an increase inthe distance between the edge of the display panel and an element in thedisplay panel, in which case the deterioration of the element due toimpurities entering from outside the display panel can be suppressed.For example, in the case where an organic EL element is used as adisplay element, impurities such as moisture or oxygen are less likelyto enter (or less likely to reach) the organic EL element from outsidethe display panel as the distance between the edge of the display paneland the organic EL element increases. Since a sufficient area of thenon-display region of the display panel can be secured in the displaydevice of one embodiment of the present invention, a highly reliablelarge display device can be fabricated even when a display panelincluding an organic EL element or the like is used.

However, the region that transmits visible light reflects or absorbs nota little visible light (e.g., light at a wavelength longer than or equalto 450 nm and shorter than or equal to 700 nm). Thus, the luminance(brightness) of a display on the display panel on the lower side mightbe different between a portion seen through the region that transmitsvisible light and a portion seen not through the region.

In view of the above, in one embodiment of the present invention, imageprocessing is performed to correct the gray scale, which is included inimage data, at the coordinates corresponding to at least one of theportion seen through the region that transmits visible light in thedisplay region and the portion seen not through the region. As a result,a difference in luminance between the portion seen through the regionthat transmits visible light and the portion seen not through the regioncan be suppressed.

FIG. 1A illustrates the image processing device of one embodiment of thepresent invention.

A first image signal S0 is supplied to an image processing device 11.The image processing device 11 supplies a second image signal S1 to adisplay device 12.

The first image signal S0 and the second image signal S1 each includeimage data (e.g., coordinate data and gray scale data) or asynchronization signal (e.g., a start pulse signal and a clock signal).

FIG. 1B illustrates the display system of one embodiment of the presentinvention.

A display system 10 includes the image processing device 11 and thedisplay device 12.

The first image signal S0 is supplied from outside the display system 10to the image processing device 11. The image processing device 11supplies the second image signal S1 to the display device 12.

FIG. 1C illustrates a structure example of the image processing device11.

The image processing device 11 includes an arithmetic portion 51 and amemory portion 52.

The first image signal S0 and correction data are supplied to thearithmetic portion 51. The arithmetic portion 51 corrects the firstimage signal S0 on the basis of the correction data to produce thesecond image signal S1. The arithmetic portion 51 can supply the secondimage signal S1 to the display device or the like. Note that in thisspecification, correction data is electrical data.

The arithmetic portion 51 includes, for example, a central processingunit (CPU) and an arithmetic circuit for image processing.

The correction data is supplied to the memory portion 52. The memoryportion 52 supplies the correction data to the arithmetic portion 51.

Examples of the correction data supplied to the image processing device11 include data acquired in advance by a camera, a luminance meter, asensor (e.g., an illuminance sensor or a color temperature sensor), anoptical inspection system of the display device, or the like, or bycalculation. A measurement result of the light transmittance (e.g.,light transmittance of material itself (internal transmittance) or lighttransmittance including surface reflection and back reflection (externaltransmittance)), light reflectance, light absorptance, or the like of aregion that transmits visible light and overlaps with a display regionof a display panel can also be used as the correction data.Alternatively, data of each display panel included in the displaydevice, such as luminance, gray scale, brightness, or chromaticity, maybe used as the correction data. Since an image taken by a camera or thelike might have a distortion, a distortion-corrected image or ananalysis result of the distortion-corrected image is preferably used asthe correction data. The image processing device 11 may have a functionof correcting a distortion of a supplied image or a function ofanalyzing a supplied image to generate correction data.

The memory portion 52 includes, for example, a memory circuit thatstores a computer program for the arithmetic portion 51 to performarithmetic processing, a look-up table, correction data calculated bythe arithmetic portion 51, the correction data supplied to the imageprocessing device 11, or the like.

Although FIG. 1C illustrates an example where the correction data issupplied from outside the image processing device 11, one embodiment ofthe present invention is not limited thereto. Examples of the correctiondata include data supplied from outside the display system 10 or outsidethe image processing device 11 and data generated in the display system10 or in the image processing device 11.

The image processing device 11 may generate correction data, forexample. Alternatively, it may be possible that the arithmetic portion51 generates correction data and supplies the correction data to thememory portion 52.

FIG. 1D illustrates another display system of one embodiment of thepresent invention.

The display system 10 includes the image processing device 11, thedisplay device 12, and a detection device 14.

The detection device 14 can acquire, for example, data of the displaydevice 12, such as luminance, gray scale, brightness, or chromaticity.Alternatively, the detection device 14 can acquire data (e.g.,illuminance or color temperature) on the ambient environment of thedisplay device 12 or the display system 10. The detection device 14 mayinclude, for example, a camera, a video camera, a luminance meter, asensor (e.g., an illuminance sensor or a color temperature sensor), oran optical inspection system of the display device. The detection device14 can supply such data (e.g., luminance data) as electrical data to theimage processing device 11.

The display system 10 may include a plurality of kinds of detectiondevices and acquire a plurality of kinds of data from which correctiondata is generated that can be used for image processing.

The detection device 14 acquires luminance data of the display device 12while the display device 12 displays an image, for example, in whichcase the detection device 14 supplies the luminance data to the imageprocessing device 11. Alternatively, the detection device 14 may acquirethe luminance data of the display device 12 while the display device 12displays white on the entire display surface, for example. Furtheralternatively, the detection device 14 may acquire a plurality of kindsof luminance data in the following manner, for example: the detectiondevice 14 acquires corresponding luminance data of the display device 12while the display device 12 displays each red, blue, and green on theentire display surface.

The luminance data may be supplied from the detection device 14 to thememory portion 52 included in the image processing device 11 and thenmay be supplied from the memory portion 52 to the arithmetic portion 51.Alternatively, the luminance data may be supplied from the detectiondevice 14 directly to the arithmetic portion 51.

The arithmetic portion 51 performs an arithmetic operation using thesupplied luminance data to generate correction data. The arithmeticportion 51 supplies the generated correction data to the memory portion52.

After the correction data is supplied to the memory portion 52, thedisplay device 12 can display an image corrected using the correctiondata. Specifically, the arithmetic portion 51 is supplied with the firstimage signal S0 from the outside and the correction data from the memoryportion 52. The arithmetic portion 51 corrects the first image signal S0using the correction data to produce the second image signal S1. Thearithmetic portion 51 supplies the second image signal 51 to the displaydevice 12. Accordingly, the display device 12 can display a correctedimage.

FIG. 2 to FIG. 4 each illustrate a structure example of the displaysystem 10.

The display systems 10 illustrated in FIG. 2 to FIG. 4 each include adecoder circuit 21, the image processing device 11, a signal dividingportion 22, a controller 23 a, a controller 23 b, and the display device12.

The display device 12 includes a plurality of display panels arranged inone or more directions. FIG. 2 illustrates an example of including twodisplay panels (a display panel 30 a and a display panel 30 b). Notethat the description given later can be referred to for the details ofthe display device 12.

In this embodiment, to distinguish the display panels from each other,the same components included in the display panels from each other, orthe same components relating to the display panels from each other,letters are added to reference numerals. Unless otherwise specified, “a”is added to reference numerals for a display panel and components placedon the lowest side (the side opposite to the display surface side), andto one or more display panels and components placed thereover, “b”, “c”,and the like are added in alphabetical order from the lower side.

The display panel 30 a includes a display region 101 a and a drivercircuit 31 a. The display panel 30 a may include a region 110 a thattransmits visible light.

The display panel 30 b includes a display region 101 b, a driver circuit31 b, and a region 110 b that transmits visible light.

The display region 101 a of the display panel 30 a has a portionoverlapping with the region 110 b that transmits visible light of thedisplay panel 30 b. In the display region 101 a, there might be adifference in recognized luminance between the portion overlapping withthe region 110 b that transmits visible light and a portion notoverlapping with the region 110 b. Thus, the image processing device 11corrects the gray scale, which is included in image data, at thecoordinates corresponding to at least one of the portion overlappingwith the region 110 b that transmits visible light and the portion notoverlapping with the region 110 b. As a result, luminance unevenness canbe reduced throughout the display region 101 a.

The gray scale of image data can be corrected in the following manner,for example: as correction data, luminance in the case where the displayregion 101 a overlaps with the region 110 b that transmits visible lightand luminance in the case where the display region 101 a does notoverlap with the region 110 b are acquired in advance, or are measuredwith a detection device, and the gray scale is corrected on the basis ofthe correction data.

Note that in the case of correcting the gray scale, which is included inimage data, at the coordinates corresponding to the portion notoverlapping with the region 110 b that transmits visible light in thedisplay region 101 a, it is preferable to correct the gray scale at thecoordinates corresponding to the display region 101 b as well.Accordingly, luminance unevenness can be reduced throughout the displaydevice 12.

A compressed or encoded image signal S10 is supplied to the decodercircuit 21. The decoder circuit 21 converts, decompresses, orreconstructs (decodes) the image signal S10 to produce an image signalS11.

In the case where the image signal S10 supplied to the display system 10is not a compressed or encoded signal but a signal the image processingdevice 11 can deal with, the decoder circuit 21 does not need to beprovided and the image signal S10 may be supplied directly to the imageprocessing device 11 or the like.

In FIG. 2, the decoder circuit 21 supplies the image signal S11 to theimage processing device 11.

The image processing device 11 corrects the supplied image signal on thebasis of the correction data to produce another image signal.

In FIG. 2, the image signal S11 is supplied to the image processingdevice 11. Then, the image processing device 11 corrects the imagesignal S11 on the basis of the correction data to produce an imagesignal S12. After that, the image processing device 11 supplies theimage signal S12 to the signal dividing portion 22.

The signal dividing portion 22 divides the supplied image signal. In thesignal dividing portion 22, the supplied image signal is divided intothe number of display panels included in the display device 12. In FIG.2, for example, since the display device 12 includes two display panels,the supplied image signal S12 is divided into two signals: an imagesignal S13 a and an image signal S13 b.

The controller 23 a supplies an image signal S14 a based on the suppliedimage signal S13 a to the driver circuit 31 a.

Similarly, the controller 23 b supplies an image signal S14 b based onthe supplied image signal S13 b to the driver circuit 31 b.

In the case where signals output from the signal dividing portion 22 aredigital signals, for example, the controller 23 a and the controller 23b preferably have functions of converting the digital signals intoanalog signals used for driving the display panel 30 a and the displaypanel 30 b. If the driver circuit 31 a and the driver circuit 31 bfunction as, or the signal dividing portion 22 functions as thecontroller 23 a and the controller 23 b, the controller 23 a and thecontroller 23 b are unnecessary.

The driver circuit 31 a drives pixels in the display region 101 a, sothat an image can be displayed on the display region 101 a. Similarly,the driver circuit 31 b drives pixels in the display region 101 b, sothat an image can be displayed on the display region 101 b.

The display panel may include a driver circuit functioning as a gatedriver circuit. For example, the driver circuit 31 a and the drivercircuit 31 b each preferably function as a gate driver circuit.Alternatively, the display device may be manufactured using a moduleincluding the display panel and an integrated circuit (IC) functioningas a gate driver circuit, without providing a gate driver circuit in thedisplay panel. The IC can be mounted on a substrate by a chip on glass(COG) method or a chip on film (COF) method. A flexible print circuit(hereinafter FPC), a tape automated bonding (TAB) tape, a tape carrierpackage (TCP), or the like on which the IC is mounted may alternativelybe used as the module.

Similarly, the display panel may include a driver circuit functioning asa source driver circuit. Alternatively, the display device may bemanufactured using a module including the display panel and an ICfunctioning as a source driver circuit, without providing a sourcedriver circuit in the display panel.

As illustrated in FIG. 3 and FIG. 4, the decoder circuit 21 may supplythe image signal S11 to the signal dividing portion 22.

As illustrated in FIG. 3, at least one of a plurality of image signalswhich are produced as a result of division by the signal dividingportion 22 is supplied to the image processing device 11.

In FIG. 3, an image signal S12 a is supplied from the signal dividingportion 22 to the image processing device 11. The image processingdevice 11 corrects the image signal S12 a on the basis of the correctiondata to produce the image signal S13 a. The image processing device 11supplies the image signal S13 a to the controller 23 a.

In addition, an image signal S12 b is supplied from the signal dividingportion 22 to the controller 23 b.

Alternatively, all of the plurality of image signals which are producedas a result of division by the signal dividing portion 22 may besupplied to the image processing device 11 as illustrated in FIG. 4.

In FIG. 4, the image signal S12 a and the image signal S12 b aresupplied from the signal dividing portion 22 to the image processingdevice 11. The image processing device 11 corrects the image signal S12a and the image signal S12 b on the basis of the correction data toproduce the image signal S13 a and the image signal S13 b. The imageprocessing device 11 supplies the image signal S13 a to the controller23 a and the image signal S13 b to the controller 23 b.

Next, examples of the correction made by the image processing device 11will be described with reference to FIGS. 5A to 5F.

In FIGS. 5A to 5F, an input value input, which is a luminance value ofimage data included in the image signal, input to the display device 12is represented by x (0≦x≦1), and an output value output, which is aluminance value, output from the display device 12 is represented by y(0≦y≦1). Note that the larger the output value y is, the brighter thescreen is (the higher the luminance is). The input value x and theoutput value y can each be converted into a gray scale value; in thecase of 256 gray scales, for example, the input value can be x (0≦x≦255)and the output value can be y (0≦y≦255). Note that when the input valuex is the luminance value, the value may be the one that has already beensubjected to gamma correction or the like (in which case the value canbe expressed by x=x₀γ₀).

Assume that a relationship between the input value x and the outputvalue y (also referred to as input-output characteristics) of theportion not overlapping with the region 110 b that transmits visiblelight in the display region 101 a of the display panel 30 a is expressedby y=x. Meanwhile, assume that input-output characteristics of theportion overlapping with the region 110 b that transmits visible lightin the display region 101 a of the display panel 30 a is expressed byy=a₀x (0<a₀<1). This means that, in the display region 101 a, luminanceis lower in the portion overlapping with the region 110 b that transmitsvisible light than in the portion not overlapping with the region 110 bthat transmits visible light. In that case, luminance unevenness occursthroughout the display panel 30 a. Note that a₀ is dependent on theoptical characteristics of the region 110 b that transmits visiblelight.

In view of the above, in one embodiment of the present invention,luminance (or gray scale) of the portion overlapping with the region 110b that transmits visible light and that of the portion not overlappingwith the region 110 b are corrected such that their input-outputcharacteristics become the same or slightly different from each other toprevent luminance unevenness throughout the display panel 30 a.

For example, the input-output characteristics of the portion notoverlapping with the region 110 b that transmits visible light in thedisplay region 101 a are corrected so as to satisfy y=ax (0<a<1), asshown in FIG. 5A. Specifically, the image processing device 11 producesthe second image signal S1 including gray scale data, which is obtainedby correcting gray scale data included in the first image signal S0using such a correction formula, and outputs the second image signal S1to the display device 12. By such correction, luminance unevennessthroughout the display device 12 can be suppressed. Note that a can becalculated using at least one of the luminance data of the displaydevice 12; the light transmittance, light reflectance, and lightabsorptance of the region 110 b that transmits visible light; and thelike.

Note that the correction may be made for all sub-pixels (e.g., a red (R)pixel, a green (G) pixel, and a blue (B) pixel) included in one pixel atthe same degree (using the same value of a), or may be performed atdifferent degrees (e.g., using a_(R), a_(G), and a_(B)) for eachsub-pixel. For example, if the luminance data of the display device 12is acquired by the detection device 14 in each case where red, blue, andgreen are displayed, the average luminance may be calculated for eachcase to determine a_(R), a_(G), and a_(B) such that the luminance ofeach sub-pixel becomes the average luminance.

In the case where a corrected image signal is supplied to both thedisplay panel 30 a and the display panel 30 b as illustrated in FIG. 2and FIG. 4, the luminance at the coordinates corresponding to at leastone of the display region 101 b and the portion not overlapping with theregion 110 b that transmits visible light in the display region 101 acan be corrected, for example.

The input-output characteristics of the display region 101 b, as well asthose of the portion not overlapping with the region 110 b thattransmits visible light in the display region 101 a, are corrected so asto satisfy y=ax (0<a<1) as shown in FIG. 5A, for example, wherebyluminance unevenness throughout the display device 12 can be suppressed.

In the case where a corrected image signal is supplied only to thedisplay panel 30 a as illustrated in FIG. 3, the luminance, which isincluded in image data, at the coordinates corresponding to the portionoverlapping with the region 110 b that transmits visible light in thedisplay region 101 a can be corrected, for example.

The input-output characteristics of the portion overlapping with theregion 110 b that transmits visible light in the display region 101 aare corrected so as to satisfy y=x/a (0<a<1) as shown in FIG. 5B, forexample, whereby luminance unevenness throughout the display device 12can be suppressed.

Note that the input value x and the output value y of the display deviceare not always proportional to each other. It is generally known thatthe input-output characteristics of a display device can be approximatedby the formula y=x^(γ) as shown in FIG. 5C.

In such a case, the input-output characteristics of the portion notoverlapping with the region 110 b that transmits visible light in thedisplay region 101 a and those of the display region 101 b are correctedso as to satisfy y=ax^(γ) (0<a<1) as shown in FIG. 5D, for example,whereby luminance unevenness throughout the display device 12 can besuppressed.

In one embodiment of the present invention, the image signal may besubjected to gamma correction in addition to the correction based on thevalue a.

Specifically, the input-output characteristics of the portionoverlapping with the region 110 b that transmits visible light in thedisplay region 101 a are corrected so as to satisfy y=(x/a)^((1/γ))(0<a<1) as shown in FIG. 5E. In addition, the input-outputcharacteristics of the portion not overlapping with the region 110 bthat transmits visible light in the display region 101 a and those ofthe display region 101 b are corrected so as to satisfy y=x^((1/γ)) asshown in FIG. 5F. Accordingly, luminance unevenness throughout thedisplay device 12 can be suppressed, and an image faithful to the imagesignal supplied to the display system 10 can be displayed.

The image processing device 11 may have, as the correction data, patterndata including the correction formula for the input-outputcharacteristics, coordinate data of the display panel, and data fordetermining whether to correct for each coordinates. The pattern datamay include a plurality of correction formulae for the input-outputcharacteristics, in which case the pattern data preferably includes datafor determining whether to correct for each coordinates and data fordetermining which correction formula to be used to correct for eachcoordinates. Specific examples will be described with reference to FIGS.6A and 6B and FIGS. 7A to 7D.

A display panel illustrated in FIG. 6A includes a display region 101, aregion 120 that blocks visible light, and a region 110 that transmitsvisible light. FIG. 6B illustrates a display device in which six displaypanels illustrated in FIG. 6A are stacked.

The display region 101 a of the lowest display panel (upper left displaypanel) in FIG. 6B has a region 105 a overlapping with one region 110that transmits visible light of another display panel, and a region 105c overlapping with three regions 110 of other display panels.

The display region 101 b has the region 105 a overlapping with oneregion 110 that transmits visible light of another display panel, aregion 105 b overlapping with two regions 110 of other display panels,and the region 105 c overlapping with three regions 110 of other displaypanels.

A display region 101 c has the region 105 a overlapping with one region110 that transmits visible light of another display panel and the region105 b overlapping with two regions 110 of other display panels.

A display region 101 d and a display region 101 e each have the region105 a overlapping with one region 110 that transmits visible light ofanother display panel.

A display region 101 f does not have a region overlapping with theregion 110 that transmits visible light.

FIGS. 7A to 7D illustrate examples of the pattern data of such a displaydevice. Described here is an example where the gray scale of the portionoverlapping with the region 110 that transmits visible light in thedisplay region 101 is corrected. Note that an example where a in theabove correction formula is determined using only a value at, which isfor the case of overlapping of one region 110 that transmits visiblelight of another display panel, for correction is described here foreasy understanding; however, values used for the case of overlapping oftwo or more regions 110 (a2 in the case of two regions 110 and a3 in thecase of three regions 110, for example) may be measured or calculated tobe used for correction.

FIG. 7A illustrates pattern data for the display region 101 a.Corrections can be made as follows, for example: correction is not madeat coordinates in a region 92 a illustrated in FIG. 7A, correction usinga=a₁ is made at coordinates in a region 92 b, and correction usinga=(a₁)³ is made at coordinates in a region 92 d.

FIG. 7B illustrates pattern data for the display region 101 b.Corrections can be made as follows, for example: correction is not madeat coordinates in the region 92 a illustrated in FIG. 7B, correctionusing a=a₁ is made at coordinates in the region 92 b, correction usinga=(a₁)² is made at coordinates in a region 92 c, and correction usinga=(a₁)³ is made at coordinates in the region 92 d.

FIG. 7C illustrates pattern data for the display region 101 c.Corrections can be made as follows, for example: correction is not madeat coordinates in the region 92 a illustrated in FIG. 7C, correctionusing a=a₁ is made at coordinates in the region 92 b, and correctionusing a=(a₁)² is made at coordinates in the region 92 c.

FIG. 7D illustrates pattern data for the display region 101 d and thedisplay region 101 e. Corrections can be made as follows, for example:correction is not made at coordinates in the region 92 a illustrated inFIG. 7D and correction using a=a₁ is made at coordinates in the region92 b.

As described above, coordinate data of the display panels and patterndata including the value a corresponding to each coordinates which arebased on the shapes of the display panels or an overlapping with patternmay be acquired and stored in the image processing device 11 in advance.

Note that the correction made by the image processing device 11 is notlimited to the above. For example, sharpening such as unsharp masking,noise removal, contrast enhancement, or edge enhancement may beperformed.

The correction by the image processing device 11 is not limited tocorrection of a difference in luminance of the display region 101 abetween the portion overlapping with the region 110 b that transmitsvisible light and the portion not overlapping with the region 110 b; theimage processing device 11 may correct a difference in luminance,chromaticity, or the like throughout one display panel or between aplurality of display panels. The correction can be made on the basis ofdata on the characteristics or the ambient environment of the displaydevice 12, for example.

In the case where the display panels are displaced as illustrated inFIG. 8A, anti-aliasing is preferably performed to make the outline ofthe portion overlapping with the region 110 that transmits visible lightin the display region 101 faint. Alternatively, pattern data in the casewhere the display panels are displaced may be acquired and supplied tothe image processing device 11.

The display system of one embodiment of the present invention mayinclude flexible display devices. In that case, luminance data isacquired at the time when an image is displayed while the displaydevices are curved as illustrated in FIG. 8B, which is preferablebecause correction in the image processing device can be made moreaccurately.

In one embodiment of the present invention, at least part of the displaydevice may have flexibility. Alternatively, at least part of the displaypanel may have flexibility. The display system of one embodiment of thepresent invention preferably includes a flexible display panel.Accordingly, a large curved display system or a flexible display systemcan be fabricated, leading to an increase in use. In that case, anorganic EL element can be favorably used as a display element.

The display device or the display system preferably has high resolutionsuch as FHD (1920×1080), 4K2K (e.g., 3840×2048 or 4096×2180), or 8K4K(e.g., 7680×4320 or 8192×4320).

Specific examples of the display device 12 will be described below withreference to drawings.

FIG. 9A is a top view of the display device 12. The display device 12illustrated in FIG. 9A includes three display panels 100 illustrated inFIG. 10B arranged in one direction (a lateral direction).

FIGS. 9B and 9C are perspective views of the display device 12 differentfrom that in FIG. 9A. The display device 12 in FIGS. 9B and 9C includesfour display panels 100 illustrated in FIG. 10C arranged in a 2×2 matrix(two display panels in the longitudinal direction and the lateraldirection). FIG. 9B is a perspective view of the display device 12 onthe display surface side. FIG. 9C is a perspective view of the displaydevice 12 on the side opposite to the display surface side.

FIGS. 9A to 9C illustrate examples where each of the display panels iselectrically connected to an FPC.

A display panel which can be used for the display device 12 is describedwith reference to FIGS. 10A to 10D. FIGS. 10A to 10D illustrate examplesof a top view of the display panel 100.

The display panel 100 includes the display region 101 and a region 102.Here, the region 102 is a portion other than the display region 101 ofthe display panel 100 in a top view. The region 102 can also be referredto as a non-display region.

For example, the display panel 100 may include the frame-like region 102that surrounds the display region 101 as illustrated in FIG. 10A.

FIGS. 10B to 10D each specifically illustrate a structure of the region102. The region 102 includes the region 110 that transmits visible lightand the region 120 that blocks visible light. The region 110 thattransmits visible light and the region 120 that blocks visible light areeach adjacent to the display region 101. The region 110 that transmitsvisible light and the region 120 that blocks visible light may each beprovided along part of the outer edge of the display region 101.

In the display panel 100 illustrated in FIG. 10B, the region 110 thattransmits visible light is provided along one side of the display region101. In the display panel 100 illustrated in FIG. 10C, the region 110that transmits visible light is provided along two sides of the displayregion 101. The region 110 that transmits visible light may be providedalong three or more sides of the display region 101. The region 110 thattransmits visible light is preferably in contact with the display region101 and provided so as to extend to an end portion of the display panelas in FIG. 10B or the like.

In each of the display panels 100 in FIGS. 10B to 10D, the region 120that blocks visible light is provided along two sides of the displayregion 101. The region 120 that blocks visible light may be extendedclose to an end portion of the display panel.

Note that in each of the regions 102 illustrated in FIGS. 10B and 10C, aregion other than the region 110 that transmits visible light and theregion 120 that blocks visible light does not necessarily have visiblelight transmittance. For example, the region 110 that transmits visiblelight may be provided over the entire circumference of the display panelas illustrated in FIG. 10D.

At least part of the region 110 that transmits visible light is adjacentto the display region 101. The region 120 that blocks visible light maybe partly provided between the region 110 that transmits visible lightand the display region 101.

The display region 101 includes a plurality of pixels arranged in amatrix and can display an image. One or more display elements areprovided in each pixel. As the display element, a light-emitting elementsuch as an organic EL element, a liquid crystal element, or the like canbe used, for example.

A material that transmits visible light is used for the region 110 thattransmits visible light. A substrate, a bonding layer, or the likeincluded in the display panel 100 may also be used, for example. Thetransmittance of the region 110 that transmits visible light withrespect to visible light is preferably higher because extractionefficiency of light from the display panel under the region 110 thattransmits visible light can be increased. The region 110 that transmitsvisible light preferably has a light transmittance of higher than orequal to 70%, further preferably higher than or equal to 80%, and stillfurther preferably higher than or equal to 90% on average at awavelength longer than or equal to 450 nm and shorter than or equal to700 nm.

In the region 120 that blocks visible light, for example, a wiringelectrically connected to the pixels (or display elements) included inthe display region 101 is provided. In addition to such a wiring, drivercircuits (e.g., a scan line driver circuit and a signal line drivercircuit) for driving the pixels may be provided. Furthermore, the region120 that blocks visible light includes a terminal electrically connectedto an FPC or the like (also referred to as a connection terminal), awiring electrically connected to the terminal, and the like.

Here, a width W of the region 110 that transmits visible lightillustrated in FIGS. 10B and 10C is preferably greater than or equal to0.5 mm and less than or equal to 150 mm, further preferably greater thanor equal to 1 mm and less than or equal to 100 mm, and still furtherpreferably greater than or equal to 2 mm and less than or equal to 50mm. The region 110 that transmits visible light serves as a sealingregion. As the width W of the region 110 that transmits visible light islarger, the distance between the edge of the display panel 100 and thedisplay region 101 can become longer, in which case an entry of animpurity such as water from the outside into the display region 101 canbe suppressed. Note that the width W of the region 110 that transmitsvisible light corresponds to the shortest distance between the displayregion 101 and the edge of the display panel 100 in some cases.

In the case where an organic EL element is used as the display element,for example, the width W of the region 110 that transmits visible lightis set to be greater than or equal to 1 mm, whereby deterioration of theorganic EL element can be effectively suppressed, which leads to animprovement in reliability. Note that also in a portion other than theregion 110 that transmits visible light, the distance between the edgeof the display region 101 and the edge of the display panel 100 ispreferably in the above range.

The display device 12 in FIG. 9A includes a display panel 100 a, adisplay panel 100 b, and a display panel 100 c.

The display panel 100 b is placed so as to partly overlap with an upperside (display surface side) of the display panel 100 a. Specifically,the region 110 b that transmits visible light of the display panel 100 bis provided to overlap with the display region 101 a of the displaypanel 100 a. A region 120 b that blocks visible light of the displaypanel 100 b is provided so as not to overlap with the display region 101a of the display panel 100 a. The display region 101 b of the displaypanel 100 b is provided to overlap with a region 102 a of the displaypanel 100 a and a region 120 a that blocks visible light of the displaypanel 100 a.

Similarly, the display panel 100 c is placed so as to partly overlapwith an upper side (display surface side) of the display panel 100 b.Specifically, a region 110 c that transmits visible light of the displaypanel 100 c is provided to overlap with the display region 101 b of thedisplay panel 100 b. A region 120 c that blocks visible light of thedisplay panel 100 c is provided so as not to overlap with the displayregion 101 b of the display panel 100 b. A display region 101 c of thedisplay panel 100 c is provided to overlap with a region 102 b of thedisplay panel 100 b and the region 120 b that blocks visible light ofthe display panel 100 b.

The region 110 b that transmits visible light is provided to overlapwith the display region 101 a; thus, a user of the display device 12 cansee the entire image on the display region 101 a even when the displaypanel 100 b overlaps with a display surface of the display panel 100 a.Similarly, the region 110 c that transmits visible light is provided tooverlap with the display region 101 b; thus, a user of the displaydevice 12 can see the entire image on the display region 101 b even whenthe display panel 100 c overlaps with a display surface of the displaypanel 100 b.

The display region 101 b of the display panel 100 b overlaps with uppersides of the region 102 a and the region 120 a that blocks visiblelight; as a result, a non-display region does not exist between thedisplay region 101 a and the display region 101 b. Similarly, thedisplay region 101 c of the display panel 100 c overlaps with uppersides of the region 102 b and the region 120 b that blocks visiblelight; as a result, a non-display region does not exist between thedisplay region 101 b and the display region 101 c. Thus, a region wherethe display region 101 a, the display region 101 b, and the displayregion 101 c are placed seamlessly can serve as a display region 13 ofthe display device 12.

The display device 12 illustrated in FIGS. 9B and 9C includes thedisplay panel 100 a, the display panel 100 b, the display panel 100 c,and a display panel 100 d.

In FIGS. 9B and 9C, short sides of the display panels 100 a and 100 boverlap with each other such that part of the display region 101 a andpart of the region 110 b that transmits visible light overlap with eachother. Furthermore, long sides of the display panels 100 a and 100 coverlap with each other such that part of the display region 101 a andpart of the region 110 c that transmits visible light overlap with eachother.

In FIGS. 9B and 9C, part of the display region 101 b overlaps with partof the region 110 c that transmits visible light and part of a region110 d that transmits visible light. In addition, part of the displayregion 101 c overlaps with part of the region 110 d that transmitsvisible light.

Thus, as illustrated in FIG. 9B, a region where the display regions 101a to 101 d are placed seamlessly can serve as the display region 13 ofthe display device 12.

Here, the display panel 100 preferably has flexibility. For example, apair of substrates included in the display panel 100 preferably hasflexibility.

Thus, as illustrated in FIGS. 9B and 9C, a region near an FPC 112 a ofthe display panel 100 a can be bent so that part of the display panel100 a and part of the FPC 112 a can be placed under the display region101 b of the display panel 100 b adjacent to the FPC 112 a. As a result,the FPC 112 a can be placed without physical interference with the rearsurface of the display panel 100 b. Furthermore, when the display panel100 a and the display panel 100 b overlap with each other and are fixed,it is not necessary to consider the thickness of the FPC 112 a; thus,the top surface of the region 110 b that transmits visible light and thetop surface of the display panel 100 a can be substantially leveled.This can make an end portion of the display panel 100 b over the displayregion 101 a less noticeable.

Moreover, each display panel 100 is made flexible, in which case thedisplay panel 100 b can be curved gently so that the top surface of thedisplay region 101 b of the display panel 100 b and the top surface ofthe display region 101 a of the display panel 100 a are leveled. Thus,the display regions can be leveled except the vicinity of a region wherethe display panel 100 a and the display panel 100 b overlap with eachother, so that the display quality of an image displayed on the displayregion 13 of the display device 12 can be improved.

Although the relation between the display panel 100 a and the displaypanel 100 b is taken as an example in the above description, the samecan apply to the relation between any other two adjacent display panels.

Furthermore, to reduce the step between two adjacent display panels 100,the thickness of the display panel 100 is preferably small. For example,the thickness of the display panel 100 is preferably less than or equalto 1 mm, further preferably less than or equal to 300 μm, and stillfurther preferably less than or equal to 100 μm. The display panel ispreferably thin because the thickness or weight of the whole displaydevice can also be reduced.

FIG. 11A is a top view of the display device 12 in FIGS. 9B and 9C seenfrom the display surface side.

Here, when the region 110 that transmits visible light of the displaypanel 100 does not have sufficiently high transmittance with respect tovisible light, luminance of a displayed image may be decreased dependingon the number of display panels 100 overlapping with the display region101.

For example, in a region A in FIG. 11A, one display panel 100 c overlapswith the display region 101 a of the display panel 100 a. In a region B,two display panels 100 (the display panels 100 c and 100 d) overlap withthe display region 101 b of the display panel 100 b. In a region C,three display panels 100 (the display panels 100 b, 100 c, and 100 d)overlap with the display region 101 a of the display panel 100 a.

In such a case, image data is preferably corrected with the use of theimage processing device of one embodiment of the present invention.Specifically, it is preferable that image data be corrected so that thegray scale of the pixels is locally increased depending on the number ofdisplay panels 100 overlapping with the display region 101. In thismanner, a decrease in the display quality of the image displayed on thedisplay region 13 of the display device 12 can be suppressed.

Alternatively, the position of an end portion of the display panel 100placed on the upper side may be shifted from the position of an endportion of another display panel 100, whereby the number of displaypanels 100 overlapping with the display region 101 of the lower displaypanel 100 can be reduced.

In FIG. 11B, the display panels 100 c and 100 d over the display panels100 a and 100 b are shifted in one direction. Specifically, the displaypanels 100 c and 100 d are relatively shifted from the display panels100 a and 100 b in the positive X direction by the width W of the region110 that transmits visible light. At this time, there are two regions: aregion D in which one display panel 100 overlaps with the display region101, and a region E in which two display panels 100 overlap with thedisplay region 101.

The display panel may be shifted in a direction perpendicular to the Xdirection (Y direction). In FIG. 11C, the display panels 100 b and 100 dare shifted from the display panels 100 a and 100 c in the positive Ydirection by the width W of the region 110 that transmits visible light.

In the case where the display panel 100 placed on the upper side isshifted from the display panel 100 placed on the lower side, the shapeof the contour of a region in which the display regions 101 of thedisplay panels 100 are combined is different from a rectangular shape.Thus, to make the shape of the display region 13 of the display device12 rectangular as illustrated in FIG. 11B or 11C, the display device 12is preferably driven so that no image is displayed on regions, which areplaced outside the display region 13, in the display regions 101 of thedisplay panels 100. Considering the number of pixels in the region notdisplaying an image, the display region 101 of each display panel 100preferably includes more pixels than the number obtained by dividing thenumber of all the pixels in the display region 13 by the number of thedisplay panels 100.

Although the distance of a relative shift of the display panels 100 isset to an integral multiple of the width W of the region 110 thattransmits visible light in the above description, the distance is notlimited thereto and can be set as appropriate in consideration of theshapes of the display panels 100, the shape of the display region 13 ofthe display device 12, in which the display panels 100 are combined, orthe like.

FIGS. 12A to 12E and FIGS. 13A to 13F are examples of cross sectionalviews of the two display panels attached to each other.

In FIGS. 12A to 12E, a lower display panel includes the display region101 a, the region 110 a that transmits visible light, and the region 120a that blocks visible light. The lower display panel is electricallyconnected to the FPC 112 a. An upper display panel (display panel on thedisplay surface side) includes the display region 101 b, the region 110b that transmits visible light, and the region 120 b that blocks visiblelight. The upper display panel is electrically connected to an FPC 112b.

In FIG. 12A, the FPC 112 a and the FPC 112 b are connected to thedisplay surface side (front surface side) of the lower display panel andthe display surface side of the upper display panel, respectively.

When air exists between the region that transmits visible light of theupper display panel and the display region of the lower display panel,part of light extracted from the display region is reflected at theinterface between the display region and air and the interface betweenair and the region that transmits visible light, which may result in adecrease in luminance of the display. As a result, the light extractionefficiency of a region in which a plurality of display panels overlapwith each other might be decreased. In addition, a difference inluminance of the display region of the lower display panel might occurbetween a portion overlapping with the region that transmits visiblelight of the upper display panel and a portion not overlapping with theregion that transmits visible light of the upper display panel, so thata joint between the display panels is easily recognized by a user insome cases.

In view of the above, as illustrated in FIG. 12B, the display devicepreferably includes a light-transmitting layer 103 having a refractiveindex higher than that of air and transmitting visible light between thedisplay region and the region that transmits visible light. Thus, aircan be prevented from entering between the display region and the regionthat transmits visible light, so that the interface reflection due to adifference in refractive index can be suppressed. In addition, displayunevenness or luminance unevenness of the display device can be reduced.When there is no air in the interface between two panels, the degree ofa decrease in the luminance of the display region, which is seen throughthe region that transmits visible light, can be easily estimated; thus,the accuracy of the image processing can be improved.

Note that the transmittance of the light-transmitting layer with respectto visible light is preferably as high as possible because the lightextraction efficiency of the display device can be increased. Thelight-transmitting layer preferably has a light transmittance of higherthan or equal to 80% and further preferably higher than or equal to 90%on average at a wavelength longer than or equal to 450 nm and shorterthan or equal to 700 nm.

The difference in refractive index between the light-transmitting layerand a layer in contact with the light-transmitting layer is preferablyas small as possible because the light reflection can be suppressed. Forexample, the refractive index of the light-transmitting layer is higherthan that of air, and preferably higher than or equal to 1.3 and lowerthan or equal to 1.8. The difference in the refractive index between thelight-transmitting layer and the layer in contact with thelight-transmitting layer (e.g., a substrate included in the displaypanel) is preferably lower than or equal to 0.30, further preferablylower than or equal to 0.20, and still further preferably lower than orequal to 0.15.

It is preferred that the light-transmitting layer be detachably incontact with at least one of the lower display panel and the upperdisplay panel. In the case where the display panels included in thedisplay device are individually detachable, when malfunction occurs inone of the display panels, for example, only the defective display panelcan be easily replaced with a new display panel. The continuous use ofthe other display panel enables the display device to be used longer andat lower cost.

When there is no need to attach and detach the display panels, thedisplay panels are fixed to each other with the light-transmitting layerincluding a material having an adhesive property (adhesive or the like).

Either of an inorganic material and an organic material can be used forthe light-transmitting layer. A liquid substance, a gelatinoussubstance, or a solid substance can be used for the light-transmittinglayer.

For the light-transmitting layer, a liquid substance such as water, asolution, a fluorine-based inactive liquid, a refractive liquid, orsilicone oil can be used, for example.

In the case where the display device is inclined to the horizontal plane(a plane perpendicular to a direction in which gravity acts) or in thecase where the display device is placed so as to be perpendicular to thehorizontal plane, the viscosity of a liquid substance is preferably 1mPa·s or more, further preferably 1 Pa·s or more, still furtherpreferably 10 Pa·s or more, and yet still further preferably 100 Pa·s ormore. In the case where the display device is placed so as to beparallel to the horizontal plane, for example, the viscosity of theliquid substance is not limited thereto.

The light-transmitting layer is preferably inactive because anotherlayer included in the display device can be prevented from beingdamaged, for example.

A material contained in the light-transmitting layer is preferablynonvolatile. Accordingly, an entry of air into the interface due tovolatilization of a material used for the light-transmitting layer canbe prevented.

For the light-transmitting layer, a high molecular material can be used.For example, a resin such as an epoxy resin, an acrylic resin, asilicone resin, a phenol resin, a polyimide resin, an imide resin, apolyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB) resin, or anethylene vinyl acetate (EVA) resin can be used. Alternatively, atwo-component-mixture-type resin may be used. For example, an adhesivesheet or any of a variety of curable adhesives such as a reactivecurable adhesive, a thermosetting adhesive, an anaerobic adhesive, and aphoto curable adhesive such as an ultraviolet curable adhesivecontaining at least one of these resins may be used. The adhesives doesnot need to be cured in the case where, for example, the display panelsare not fixed to each other.

The light-transmitting layer preferably has high self-attachability toan object. In addition, the light-transmitting layer preferably has highseparability against an object. After the light-transmitting layerattached to the display panel is separated from the display panel, it ispreferred that the light-transmitting layer be able to be attached tothe display panel again.

In addition, it is preferred that the light-transmitting layer have noadhesiveness or low adhesiveness. In that case, attachment andseparation of the light-transmitting layer to and from an object can berepeated without damaging or contaminating a surface of the object.

As the light-transmitting layer, a film having attachability or a filmhaving adhesiveness can be used, for example. In the case where anattachment film having a stacked-layer structure of an attachment layeror an adhesive layer and a base material is used, the attachment layeror the adhesive layer may function as the light-transmitting layer ofthe display device of one embodiment of the present invention, and thebase material may function as a substrate included in the display panel.Note that the display device may have a substrate in addition to thebase material in the attachment film. The attachment film may include ananchor layer between the attachment layer or the adhesive layer and thebase material. The anchor layer has a function of enhancing theadhesiveness between the attachment layer or the adhesive layer and thebase material. In addition, the anchor layer has a function of smoothinga surface of the base material coated with the attachment layer or theadhesive layer. In this manner, bubbles can be made hardly generatedbetween the object and the light-transmitting layer.

A film in which a silicone resin layer and a polyester film are stackedcan be preferably used in the display device, or example. In that case,the silicone resin layer has attachability and functions as alight-transmitting layer, whereas the polyester film serves as asubstrate included in the display panel. Note that another substrate maybe included in the display panel in addition to the polyester film.

In the case where a film in which an attachment layer, a base material,and an adhesive layer or a bonding layer are stacked is used, theattachment layer functions as a light-transmitting layer of the displaydevice; the base material functions as a substrate included in thedisplay panel;

and the adhesive layer or the bonding layer functions as a layer forattaching an element layer of the display panel to the substrate.

The thickness of the light-transmitting layer is not particularlylimited and may be greater than or equal to 1 μm and less than or equalto 50 μm, for example. The thickness of the light-transmitting layer canbe greater than 50 μm; however, in the case of manufacturing a flexibledisplay device, the thickness of the display device is preferably setsuch that the flexibility of the display device is not reduced. Forexample, the thickness of the light-transmitting layer is preferablygreater than or equal to 10 μm and less than or equal to 30 μm. Thethickness of the light-transmitting layer can be less than 1 μm.

The display region 101 a overlaps with the region 110 b that transmitsvisible light with the light-transmitting layer 103 providedtherebetween. Thus, air can be prevented from entering between thedisplay region 101 a and the region 110 b that transmits visible light,so that interface reflection due to a difference in refractive index canbe reduced.

Accordingly, a difference in luminance of the display region 101 abetween a portion overlapping with the region 110 b that transmitsvisible light and a portion not overlapping with the region 110 b thattransmits visible light can be suppressed, so that a joint between thedisplay panels of the display device can be hardly recognized by a userof the display device. In addition, display unevenness or luminanceunevenness of the display device can be suppressed.

The region 120 a that blocks visible light and the FPC 112 a eachoverlap with the display region 101 b. Thus, a sufficient area of anon-display region can be secured and a seamless display region can beincreased in size, so that a highly reliable large display device can befabricated.

In FIG. 12C, the FPC 112 a and the FPC 112 b are connected to the side(rear surface side) opposite to the display surface of the lower displaypanel and the side (rear surface side) opposite to the display surfaceof the upper display panel, respectively.

As illustrated in FIG. 12C, the light-transmitting layer 103 may also beprovided between the region 120 a that blocks visible light of the lowerdisplay panel and the display region 101 b of the upper display panel.

When an FPC is connected to the rear surface side of a lower displaypanel, an end portion of the display panel can be attached to the rearsurface of an upper display panel; thus, the attachment area can beincreased and the mechanical strength of the attached portion can beincreased.

As illustrated in FIG. 12D, the light-transmitting layer 103 may overlapwith a region of the display region 101 a not overlapping with the upperdisplay panel. Furthermore, the region 110 a that transmits visiblelight and the light-transmitting layer 103 may overlap with each other.

As illustrated in FIG. 12E, the light-transmitting layer 103 may overlapwith a region of the upper display panel not overlapping with thedisplay region 101 a.

As illustrated in FIG. 13A, the lower display panel may include asubstrate 151 a, a substrate 152 a, and an element layer 153 a, and theupper display panel may include a substrate 151 b, a substrate 152 b,and an element layer 153 b, for example.

The element layer 153 a has a region 155 a including a display elementand a region 156 a including a wiring electrically connected to thedisplay element. The wiring included in the region 156 a is electricallyconnected to the FPC 112 a.

Similarly, the element layer 153 b of the upper display panel has aregion 155 b including a display element and a region 156 b including awiring electrically connected to the display element. The wiringincluded in the region 156 b is electrically connected to the FPC 112 b.

A light-transmitting layer 103 a is provided over the substrate 152 a.For example, a stack of the substrate 152 a and the light-transmittinglayer 103 a can be formed using the above-described attachment filmhaving a stack of an attachment layer and a base material. The substrate152 b and a light-transmitting layer 103 b can have a similar structure.

Here, fine dirt such as dust in the air might be attached depending on amaterial of the light-transmitting layer. In such a case, it ispreferable that the region of the display region 101 a not overlappingwith the upper display panel do not overlap with the light-transmittinglayer 103. This makes it possible to prevent unclear display of thedisplay device due to dirt or the like attached to thelight-transmitting layer 103.

As illustrated in FIG. 13B, the light-transmitting layer 103 a may be incontact with the substrate 151 a. For example, a stack of the substrate151 a and the light-transmitting layer 103 a can be formed using theabove-described attachment film having a stack of an attachment layerand a base material. The substrate 151 b and the light-transmittinglayer 103 b can have a similar structure.

In the structure illustrated in FIG. 13B, the light-transmitting layeris not provided on the outermost surface of the display surface of thedisplay device; thus, unclear display of the display device due to dirtor the like attached to the light-transmitting layer 103 can beprevented. In addition, when a light-transmitting layer havingattachability is provided on the rear surface of the display device, thedisplay device can be detachably attached to a desired portion with theuse of a surface of the light-transmitting layer which is not in contactwith the display panel.

Alternatively, as illustrated in FIG. 13C, a resin layer 131 whichcovers front surfaces of the display panel 100 a and the display panel100 b may be provided. Specifically, the resin layer 131 is preferablyprovided to cover the display regions of the display panels 100 a and100 b and a region where the display panel 100 a overlap with thedisplay panel 100 b.

Providing the resin layer 131 over the plurality of display panels 100can increase the mechanical strength of the display device 12. Inaddition, the resin layer 131 is formed to have a flat surface, wherebythe display quality of an image displayed on the display region 13 canbe increased. For example, when a coating apparatus such as a slitcoater, a curtain coater, a gravure coater, a roll coater, or a spincoater is used, the resin layer 131 with high flatness can be formed.

The refractive index of the resin layer 131 is preferably 0.8 to 1.2times, further preferably 0.9 to 1.1 times, and still further preferably0.95 to 1.15 times as high as the refractive index of the substrate onthe display surface side of the display panel 100. Light can beextracted outside more efficiently as the difference in refractive indexbetween the display panel 100 and the resin layer 131 becomes smaller.In addition, the resin layer 131 with such a refractive index isprovided to cover a step portion between the display panel 100 a and thedisplay panel 100 b, whereby the step portion is not easily recognizedvisually, and the display quality of an image displayed on the displayregion 13 can be increased.

The resin layer 131 transmits visible light. For the resin layer 131,for example, an organic resin such as an epoxy resin, an aramid resin,an acrylic resin, a polyimide resin, a polyamide resin, or apolyamide-imide resin can be used.

Alternatively, as illustrated in FIG. 13D, a protective substrate 132 ispreferably provided over the display device 12 with the resin layer 131provided therebetween. In that case, the resin layer 131 may serve as abonding layer for bonding the protective substrate 132 to the displaydevice 12. With the protective substrate 132, the surface of the displaydevice 12 can be protected, and moreover, the mechanical strength of thedisplay device 12 can be increased. For the protective substrate 132, alight-transmitting material is used at least in a region overlappingwith the display region 13. Furthermore, the protective substrate 132may have a light-blocking property in a region other than the regionoverlapping with the display region 13 so as not to be visuallyrecognized.

The protective substrate 132 may function as a touch panel. In the casewhere the display panel 100 is flexible and capable of being bent, theprotective substrate 132 is also preferably flexible.

Furthermore, a difference in refractive index between the protectivesubstrate 132 and the substrate on the display surface side of thedisplay panel 100 or the resin layer 131 is preferably less than orequal to 20%, further preferably less than or equal to 10%, and stillfurther preferably less than or equal to 5%.

As the protective substrate 132, a plastic substrate that is formed as afilm can be used. For the plastic substrate, a polyester resin such aspolyethylene terephthalate (PET) or polyethylene naphthalate (PEN), apolyacrylonitrile resin, a polyimide resin, a polymethyl methacrylateresin, a polycarbonate (PC) resin, a poly ethersulfone (PES) resin, apolyamide resin (e.g., nylon or aramid), a polycycloolefin resin, apolystyrene resin, a polyamide imide resin, a polyvinyl chloride resin,a polyetheretherketone (PEEK) resin, a polysulfone (PSF) resin, apolyetherimide (PEI) resin, a poly arylate (PAR) resin, a polybutyleneterephthalate (PBT) resin, a polytetrafluoroethylene (PTFE) resin, asilicone resin, or the like can be used. Alternatively, a substrate inwhich a fibrous body is impregnated with a resin (also referred to asprepreg) or a substrate whose coefficient of linear expansion is reducedby mixing an organic resin with an inorganic filler can be used. Theprotective substrate 132 is not limited to the resin film, and atransparent nonwoven fabric formed by processing pulp into a continuoussheet, a sheet including an artificial spider's thread fiber containingprotein called fibroin, a complex in which the transparent nonwovenfabric or the sheet and a resin are mixed, a stack of a resin film and anonwoven fabric containing a cellulose fiber whose fiber width is 4 nmor more and 100 nm or less, or a stack of a resin film and a sheetincluding an artificial spider's thread fiber may be used.

As the protective substrate 132, at least one of a polarizing plate, acircular polarizing plate, a retardation plate, an optical film, and thelike may be used.

As illustrated in FIG. 13E, a resin layer 133 and a protective substrate134 may be provided on surfaces opposite to the display surfaces of thedisplay panels 100 a and 100 b. Providing a substrate supporting thedisplay panels on the rear surfaces of the display panels can suppressunintended warping or bending of the display panels, whereby the displaysurfaces can be kept smooth. Thus, the display quality of an imagedisplayed on the display region 13 can be improved.

Note that the resin layer 133 and the protective substrate 134, whichare provided on the sides opposite to the display surfaces, do notnecessarily have light transmittance, and a material which absorbs orreflects visible light may be used.

As illustrated in FIG. 13F, the resin layer 131 and the protectivesubstrate 132 may be provided on the front surfaces of the displaypanels, and the resin layer 133 and the protective substrate 134 may beprovided on the rear surfaces thereof. In this manner, the displaypanels 100 a and 100 b are sandwiched between the two protectivesubstrates, whereby the mechanical strength of the display device 12 canbe further increased.

It is preferable that the total thickness of the resin layer 131 and theprotective substrate 132 be approximately the same as that of the resinlayer 133 and the protective substrate 134. For example, it ispreferable that the thicknesses of the resin layers 131 and 133 be madesubstantially equal to each other, and materials having the samethickness be used for the protective substrates 132 and 134. In thatcase, the plurality of display panels 100 can be located at the centerof the stack in the thickness direction. For example, when the stackincluding the display panels 100 at the center in the thicknessdirection is bent, stress in the lateral direction applied to thedisplay panels 100 by bending can be relieved, which prevents thedisplay panels 100 from being damaged.

In the case where the thicknesses of the resin layer and the protectivesubstrate differ between an end portion and a center portion of thedisplay device, for example, the total thickness of the resin layer 131and the protective substrate 132 and that of the resin layer 133 and theprotective substrate 134 are preferably compared under the samecondition which is appropriately selected from conditions such as theaverage thickness, the largest thickness, the smallest thickness, andthe like.

In FIG. 13F, the same material is preferably used for the resin layers131 and 133 because the manufacturing cost can be reduced. Similarly,the same material is preferably used for the protective substrates 132and 134 because the manufacturing cost can be reduced.

As illustrated in FIGS. 13E and 13F, an opening for leading the FPC 112a is preferably provided in the resin layer 133 and the protectivesubstrate 134, which are located on the rear surface sides of thedisplay panels 100 a and 100 b. In particular, when the resin layer 133is provided to cover part of the FPC 112 a as illustrated in FIG. 13F,the mechanical strength at a connection portion between the displaypanel 100 a and the FPC 112 a can be increased, and defects such asseparation of the FPC 112 a can be suppressed. Similarly, the resinlayer 133 is preferably provided to cover part of the FPC 112 b.

Next, a structure example of the display panel 100 will be described.FIG. 14A is an example of a top view in which a region Pin FIG. 10C isenlarged, and FIG. 14B is an example of a top view in which a region Qin FIG. 10C is enlarged.

As illustrated in FIG. 14A, a plurality of pixels 141 are arranged in amatrix in the display region 101. In the case where the display panel100 capable of full color display with three colors of red, blue, andgreen is formed, each of the pixels 141 corresponds to a sub-pixelcapable of displaying any of the three colors. A sub-pixel capable ofdisplaying white or yellow may be provided in addition to the sub-pixelscapable of displaying any of the three colors. A region including thepixels 141 corresponds to the display region 101.

A wiring 142 a and a wiring 142 b are electrically connected to eachpixel 141. Each of the plurality of wirings 142 a intersects with thewiring 142 b, and is electrically connected to a circuit 143 a. Theplurality of wirings 142 b are electrically connected to a circuit 143b. One of the circuits 143 a and 143 b can function as a scan linedriver circuit, and the other can function as a signal line drivercircuit. One or both of the circuits 143 a and 143 b are not necessarilyprovided.

In FIG. 14A, a plurality of wirings 145 electrically connected to thecircuit 143 a or the circuit 143 b are provided. The wiring 145 iselectrically connected to an FPC 123 in an unillustrated region and hasa function of supplying a signal from the outside to the circuits 143 aand 143 b.

In FIG. 14A, a region including the circuit 143 a, the circuit 143 b,the plurality of wirings 145, and the like corresponds to the region 120that blocks visible light.

In FIG. 14B, a region outside the pixel 141 provided closest to the endcorresponds to the region 110 that transmits visible light. The region110 that transmits visible light does not include members that blocksvisible light, such as the pixel 141, the wiring 142 a, and the wiring142 b. Note that in the case where part of the pixel 141, the wiring 142a, or the wiring 142 b transmits visible light, the part of the pixel141, the wiring 142 a, or the wiring 142 b may be provided to extend tothe region 110 that transmits visible light.

In the case where the width of the region 110 that transmits visiblelight varies within one display panel, or in the case where the widthvaries depending on the positions of the same display panel, theshortest length can be referred to as the width W. In FIG. 14B, thedistance between the pixel 141 and the end portion of the substrate(that is, the width W of the region 110 that transmits visible light) inthe longitudinal direction is the same as that in the lateral direction,but one embodiment of the present invention is not limited thereto.

FIG. 14C is a cross-sectional view taken along line A1-A2 in FIG. 14B.The display panel 100 includes a pair of substrates (a substrate 151 anda substrate 152) that transmits visible light. The substrate 151 and thesubstrate 152 are bonded to each other with a bonding layer 154. Here,the substrate on which the pixel 141, the wiring 142 b, and the like areformed is referred to as the substrate 151.

As illustrated in FIGS. 14B and 14C, in the case where the pixel 141 ispositioned closest to the end of the display region 101, the width W ofthe region 110 that transmits visible light is the distance between anend portion of the substrate 151 or the substrate 152 and an end portionof the pixel 141.

Note that the end portion of the pixel 141 refers to an end portion of amember that is positioned closest to the end and blocks visible light inthe pixel 141. Alternatively, in the case where a light-emitting elementincluding a layer containing a light-emitting organic compound between apair of electrodes (also referred to as an organic EL element) is usedas the pixel 141, the end portion of the pixel 141 may be any of an endportion of a lower electrode, an end portion of the layer containing alight-emitting organic compound, and an end portion of an upperelectrode.

FIG. 15A is an example of a top view in which the region Q is enlarged;the position of the wiring 142 a is different from that in FIG. 14B.FIG. 15B is a cross-sectional view taken along line B1-B2 in FIG. 15A,and FIG. 15C is a cross sectional view taken along line C1-C2 in FIG.15A.

As illustrated in FIGS. 15A to 15C, in the case where the wiring 142 ais positioned closest to the end of the display region 101, the width Wof the region 110 that transmits visible light is the distance betweenthe end portion of the substrate 151 or the substrate 152 and the endportion of the wiring 142 a. In the case where the wiring 142 atransmits visible light, the region 110 that transmits visible light mayinclude a region where the wiring 142 a is provided.

Here, in the case where the density of pixels provided in the displayregion 101 of the display panel 100 is high, misalignment may occur whentwo display panels 100 are bonded.

FIGS. 16A to 16C each illustrate a positional relation between thedisplay region 101 a of the display panel 100 a provided on the lowerside and the display region 101 b of the display panel 100 b provided onthe upper side, seen from the display surface side. FIGS. 16A to 16Ceach illustrate the vicinities of the corner portions of the displayregions 101 a and 101 b. Part of the display region 101 a is coveredwith the region 110 b that transmits visible light.

FIG. 16A illustrates the case where adjacent pixels 141 a and 141 b arerelatively deviated in one direction (Y direction). The arrow in thedrawing denotes a direction in which the display panel 100 a is deviatedfrom the display panel 100 b.

FIG. 16B shows an example in which the adjacent pixels 141 a and 141 bare relatively deviated in a longitudinal direction and a lateraldirection (X direction and Y direction).

In the examples illustrated in FIGS. 16A and 16B, the deviation in thelateral direction or the longitudinal direction is smaller than thewidth of one pixel. In such a case, image data corresponding to an imageto be displayed on at least one of the display region 101 a and thedisplay region 101 b is corrected on the basis of the deviation, wherebythe display quality can be maintained. Specifically, when the deviationmakes the distance between pixels smaller, the correction is preferablymade such that the gray scale (luminance) of the pixels is decreased. Incontrast, when the deviation makes the distance between pixels larger,the correction is preferably made such that the gray scale (luminance)of the pixels is increased. In the case where the display region 101 boverlaps over the display region 101 a by more than the width of onepixel, image data is preferably corrected to shift by one column suchthat the pixel 141 a positioned under the pixel 141 b is not driven.

FIG. 16C illustrates an example in which the pixels 141 a and 141 b,which should be adjacent to each other, are relatively deviated in onedirection (Y direction) by a length of more than one pixel. When thedeviation of more than one pixel occurs, the pixels are preferablydriven so that projecting pixels (pixels which are hatched) are notdisplayed. Note that the same applies to the case where the deviationdirection is the X direction.

When the plurality of display panels 100 are bonded, in order tosuppress misalignment, each of the display panels 100 is preferablyprovided with an alignment marker or the like. Alternatively, aprojection and a depression may be formed on the surfaces of the displaypanels 100, and the projection and the depression may fit together in aregion where two display panels 100 overlap with each other.

In consideration of alignment accuracy, it is preferable that pixelsmore than the pixels to be used be placed in advance in the displayregion 101 of the display panel 100. For example, it is preferable thatone or more, preferably three or more, and further preferably five ormore extra pixel columns along either one or both of a scan line and asignal line be provided in addition to the pixel columns used fordisplay.

As described above, the image processing device of one embodiment of thepresent invention can perform image processing to correct the grayscale, which is included in image data, at the coordinates correspondingto at least one of the portion seen through the region that transmitsvisible light in the display region of the display panel and the portionseen not through the region.

As a result, a difference in luminance between the portion seen throughthe region that transmits visible light and the portion seen not throughthe region can be suppressed. Thus, a large display system in which ajoint between the display panels is hardly recognized and displayunevenness or luminance unevenness is suppressed can be obtained.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 2

In this embodiment, light-emitting panels, each of which is an exampleof a display panel that can be used for the display system of oneembodiment of the present invention, will be described with reference todrawings.

Although a light-emitting panel including an organic EL element will bemainly described as an example in this embodiment, a panel that can beused for the display system of one embodiment of the present inventionis not limited to this example.

Specific Example 1

FIG. 17A is a plan view of a light-emitting panel, and FIG. 17C is anexample of a cross-sectional view taken along dashed-dotted line A1-A2in FIG. 17A. FIG. 17C also illustrates an example of a cross-sectionalview of the region 110 that transmits visible light. The light-emittingpanel described in Specific Example 1 is a top-emission light-emittingpanel using a color filter method. In this embodiment, thelight-emitting panel can have a structure in which sub-pixels of threecolors of red (R), green (G), and blue (B) express one color, astructure in which sub-pixels of four colors of R, G, B, and white (W)express one color, a structure in which sub-pixels of four colors of R,G, B, and yellow (Y) express one color, or the like. There is noparticular limitation on the color element and colors other than R, G,B, W, and Y may be used. For example, cyan, magenta, or the like may beused.

The light-emitting panel illustrated in FIG. 17A includes the region 110that transmits visible light, a light-emitting portion 804, a drivercircuit portion 806, and an FPC 808. The region 110 that transmitsvisible light is adjacent to the light-emitting portion 804, and isplaced along two sides of the light-emitting portion 804.

The light-emitting panel illustrated in FIG. 17C includes a substrate701, a bonding layer 703, an insulating layer 705, a plurality oftransistors, a conductive layer 857, an insulating layer 815, aninsulating layer 817, a plurality of light-emitting elements, aninsulating layer 821, a bonding layer 822, a coloring layer 845, alight-blocking layer 847, an insulating layer 715, a bonding layer 713,and a substrate 711. The bonding layer 822, the insulating layer 715,the bonding layer 713, and the substrate 711 transmit visible light. Thelight-emitting elements and the transistors included in thelight-emitting portion 804 and the driver circuit portion 806 are sealedwith the substrate 701, the substrate 711, and the bonding layer 822.

The light-emitting portion 804 includes a transistor 820 and alight-emitting element 830 over the substrate 701 with the bonding layer703 and the insulating layer 705 provided therebetween. Thelight-emitting element 830 includes a lower electrode 831 over theinsulating layer 817, an EL layer 833 over the lower electrode 831, andan upper electrode 835 over the EL layer 833. The lower electrode 831 iselectrically connected to a source electrode or a drain electrode of thetransistor 820. An end portion of the lower electrode 831 is coveredwith the insulating layer 821. The lower electrode 831 preferablyreflects visible light. The upper electrode 835 transmits visible light.

The light-emitting portion 804 also includes the coloring layer 845overlapping with the light-emitting element 830 and the light-blockinglayer 847 overlapping with the insulating layer 821. The space betweenthe light-emitting element 830 and the coloring layer 845 is filled withthe bonding layer 822.

The insulating layer 815 has an effect of suppressing diffusion ofimpurities into semiconductors included in the transistors. As theinsulating layer 817, an insulating layer having a planarizationfunction is preferably selected in order to reduce surface unevennessdue to the transistors.

The driver circuit portion 806 includes a plurality of transistors overthe substrate 701 with the bonding layer 703 and the insulating layer705 provided therebetween. In FIG. 17C, one of the transistors includedin the driver circuit portion 806 is illustrated.

The insulating layer 705 and the substrate 701 are attached to eachother with the bonding layer 703. The insulating layer 715 and thesubstrate 711 are attached to each other with the bonding layer 713. Atleast one of the insulating layer 705 and the insulating layer 715 ispreferably highly resistant to moisture, in which case impurities suchas water can be prevented from entering the light-emitting element 830and the transistor 820, leading to higher reliability of thelight-emitting panel.

The conductive layer 857 is electrically connected to an external inputterminal through which a signal (e.g., a video signal, a clock signal, astart signal, or a reset signal) or a potential from the outside istransmitted to the driver circuit portion 806. Here, an example isdescribed in which the FPC 808 is provided as the external inputterminal. To prevent an increase in the number of fabrication steps, theconductive layer 857 is preferably formed using the same material andstep as any of the electrodes and the wirings in the light-emittingportion and the driver circuit portion. Described here is an example inwhich the conductive layer 857 is formed using the same material andstep as the electrode included in the transistor 820.

In the light-emitting panel illustrated in FIG. 17C, the FPC 808 ispositioned over the substrate 711. A connector 825 is connected to theconductive layer 857 through an opening provided in the substrate 711,the bonding layer 713, the insulating layer 715, the bonding layer 822,the insulating layer 817, and the insulating layer 815. The connector825 is also connected to the FPC 808. The FPC 808 and the conductivelayer 857 are electrically connected to each other via the connector825. In the case where the conductive layer 857 overlaps with thesubstrate 711, an opening in the substrate 711 (or the use of asubstrate having an opening portion) allows the connector 825 to beelectrically connected to the conductive layer 857 and the FPC 808.

FIG. 18 is an example of a cross-sectional view of a display deviceincluding two light-emitting panels illustrated in FIG. 17B that overlapwith each other. FIG. 18 illustrates the display region 101 a(corresponding to the light-emitting portion 804 in FIG. 17B) and theregion 120 a that blocks visible light (corresponding to the drivercircuit portion 806 and the like in FIG. 17B) of a lower light-emittingpanel, and the display region 101 b (corresponding to the light-emittingportion 804 in FIG. 17B) and the region 110 b that transmits visiblelight (corresponding to the region 110 that transmits visible light inFIG. 17B) of an upper light-emitting panel.

In the display device illustrated in FIG. 18, the light-emitting panelpositioned on the display surface side (upper side) includes the region110 b that transmits visible light adjacent to the display region 101 b.The display region 101 a of the lower light-emitting panel and theregion 110 b that transmits visible light of the upper light-emittingpanel overlap with each other. Thus, a non-display region that appearsbetween the display regions of the two light-emitting panels overlappingwith each other can be reduced or even removed. Accordingly, a largedisplay device in which a joint between light-emitting panels is hardlyrecognized by a user can be obtained.

The display device illustrated in FIG. 18 includes a light-transmittinglayer 103 having a refractive index higher than that of air andtransmitting visible light between the display region 101 a and theregion 110 b that transmits visible light. In that case, air can beprevented from entering between the display region 101 a and the region110 b that transmits visible light, so that the interface reflection dueto a difference in refractive index can be reduced. In addition, displayunevenness or luminance unevenness of the display device can besuppressed.

The light-transmitting layer 103 may overlap with the entire surface ofthe substrate 711 of the lower light-emitting panel or that of thesubstrate 701 of the upper light-emitting panel, or may overlap withonly the display region 101 a and the region 110 b that transmitsvisible light. In addition, the substrate 711 and the light-transmittinglayer 103 may be included in the region 120 a that blocks visible light.

The stack of the substrate 701 of the upper light-emitting panel and thelight-transmitting layer 103 can be formed using, for example, anattachment film having a stack of an attachment layer and a basematerial.

Specific Example 2

FIG. 17B is a plan view of a light-emitting panel, and FIG. 19A is anexample of a cross-sectional view taken along dashed-dotted line A3-A4in FIG. 17B. The light-emitting panel described in Specific Example 2 isa top-emission light-emitting panel using a color filter method, whichis different from that described in Specific Example 1. Portionsdifferent from those in Specific Example 1 will be described in detailhere and the descriptions of portions common to those in SpecificExample 1 will be omitted.

FIG. 17B illustrates an example where the region 110 that transmitsvisible light is provided along three sides of the light-emitting panel.The region 110 that transmits visible light is adjacent to thelight-emitting portion 804 on two sides among the three sides.

The light-emitting panel illustrated in FIG. 19A is different from thatin FIG. 17C in the following respects.

The light-emitting panel illustrated in FIG. 19A includes insulatinglayers 817 a and 817 b and a conductive layer 856 over the insulatinglayer 817 a. The source electrode or the drain electrode of thetransistor 820 and the lower electrode of the light-emitting element 830are electrically connected to each other through the conductive layer856.

The light-emitting panel illustrated in FIG. 19A includes a spacer 823over the insulating layer 821. The spacer 823 can adjust the distancebetween the substrate 701 and the substrate 711.

The light-emitting panel illustrated in FIG. 19A includes an overcoat849 covering the coloring layer 845 and the light-blocking layer 847.The space between the light-emitting element 830 and the overcoat 849 isfilled with the bonding layer 822.

In the light-emitting panel illustrated in FIG. 19A, the substrate 701differs from the substrate 711 in size. The FPC 808 is located over theinsulating layer 715 and does not overlap with the substrate 711. Theconnector 825 is connected to the conductive layer 857 through anopening provided in the insulating layer 715, the bonding layer 822, theinsulating layer 817 a, the insulating layer 817 b, and the insulatinglayer 815. Since no opening needs to be provided in the substrate 711,there is no limitation on the material of the substrate 711.

Note that as illustrated in FIG. 19B, the light-emitting element 830 mayinclude an optical adjustment layer 832 between the lower electrode 831and the EL layer 833. A light-transmitting conductive material ispreferably used for the optical adjustment layer 832. Owing to thecombination of a color filter (the coloring layer) and a microcavitystructure (the optical adjustment layer), light with high color puritycan be extracted from the display system of one embodiment of thepresent invention. The thickness of the optical adjustment layer isvaried depending on the emission color of the sub-pixel.

Specific Example 3

FIG. 17B is a plan view of a light-emitting panel, and FIG. 19C isanother example of a cross-sectional view taken along dashed-dotted lineA3-A4 in FIG. 17B. The light-emitting panel described in SpecificExample 3 is a top-emission light-emitting panel using a separatecoloring method.

The light-emitting panel in FIG. 19C includes the substrate 701, thebonding layer 703, the insulating layer 705, a plurality of transistors,the conductive layer 857, the insulating layer 815, the insulating layer817, a plurality of light-emitting elements, the insulating layer 821,the spacer 823, the bonding layer 822, and the substrate 711. Thebonding layer 822 and the substrate 711 transmit visible light.

In the light-emitting panel illustrated in FIG. 19C, the connector 825is positioned over the insulating layer 815. The connector 825 isconnected to the conductive layer 857 through an opening provided in theinsulating layer 815. The connector 825 is also connected to the FPC808. The FPC 808 and the conductive layer 857 are electrically connectedto each other via the connector 825.

Specific Example 4

FIG. 17B is a plan view of a light-emitting panel, and FIG. 20A isanother example of a cross-sectional view taken along dashed-dotted lineA3-A4 in FIG. 17B. The light-emitting panel described in SpecificExample 4 is a bottom-emission light-emitting panel using a color filtermethod.

The light-emitting panel in FIG. 20A includes the substrate 701, thebonding layer 703, the insulating layer 705, a plurality of transistors,the conductive layer 857, the insulating layer 815, the coloring layer845, the insulating layer 817 a, the insulating layer 817 b, theconductive layer 856, a plurality of light-emitting elements, theinsulating layer 821, the bonding layer 822, and the substrate 711. Thesubstrate 701, the bonding layer 703, the insulating layer 705, theinsulating layer 815, the insulating layer 817 a, and the insulatinglayer 817 b transmit visible light.

The light-emitting portion 804 includes the transistor 820, a transistor824, and the light-emitting element 830 over the substrate 701 with thebonding layer 703 and the insulating layer 705 provided therebetween.The light-emitting element 830 includes the lower electrode 831 over theinsulating layer 817 b, the EL layer 833 over the lower electrode 831,and the upper electrode 835 over the EL layer 833. The lower electrode831 is electrically connected to a source electrode or a drain electrodeof the transistor 820. An end portion of the lower electrode 831 iscovered with the insulating layer 821. The upper electrode 835preferably reflects visible light. The lower electrode 831 transmitsvisible light. The coloring layer 845 that overlaps with thelight-emitting element 830 can be provided anywhere; for example, thecoloring layer 845 can be provided between the insulating layers 817 aand 817 b or between the insulating layers 815 and 817 a.

The driver circuit portion 806 includes a plurality of transistors overthe substrate 701 with the bonding layer 703 and the insulating layer705 provided therebetween. In FIG. 20A, two of the transistors includedin the driver circuit portion 806 are illustrated.

The insulating layer 705 and the substrate 701 are attached to eachother with the bonding layer 703. The insulating layer 705 is preferablyhighly resistant to moisture, in which case impurities such as water canbe prevented from entering the light-emitting element 830, thetransistor 820, and the transistor 824, leading to higher reliability ofthe light-emitting panel.

The conductive layer 857 is electrically connected to an external inputterminal through which a signal or a potential from the outside istransmitted to the driver circuit portion 806. Described here is anexample in which the FPC 808 is provided as the external input terminaland the conductive layer 857 is formed using the same material and thesame step as the conductive layer 856.

Specific Example 5

FIG. 20B illustrates an example of a light-emitting panel that isdifferent from those in Specific Examples 1 to 4.

The light-emitting panel in FIG. 20B includes the substrate 701, thebonding layer 703, the insulating layer 705, a conductive layer 814, aconductive layer 857 a, a conductive layer 857 b, the light-emittingelement 830, the insulating layer 821, the bonding layer 822, and thesubstrate 711.

The conductive layer 857 a and the conductive layer 857 b, which areexternal connection electrodes of the light-emitting panel, can each beelectrically connected to an FPC or the like.

The light-emitting element 830 includes the lower electrode 831, the ELlayer 833, and the upper electrode 835. An end portion of the lowerelectrode 831 is covered with the insulating layer 821. Thelight-emitting element 830 is a bottom-emission, top-emission, ordual-emission light-emitting element. An electrode, a substrate, aninsulating layer, and the like on the light extraction side transmitvisible light. The conductive layer 814 is electrically connected to thelower electrode 831.

The substrate through which light is extracted may have, as a lightextraction structure, a hemispherical lens, a micro lens array, a filmprovided with an uneven surface structure, a light diffusing film, orthe like. For example, a substrate having the light extraction structurecan be formed by bonding the above lens or film to a resin substratewith an adhesive or the like having substantially the same refractiveindex as the substrate or the lens or film.

The conductive layer 814 is preferably, though not necessarily, providedbecause voltage drop due to the resistance of the lower electrode 831can be prevented. For a similar purpose, a conductive layer electricallyconnected to the upper electrode 835 may be provided over the insulatinglayer 821, the EL layer 833, the upper electrode 835, or the like.

The conductive layer 814 can be formed to have a single layer or astacked layer using a material selected from copper, titanium, tantalum,tungsten, molybdenum, chromium, neodymium, scandium, nickel, andaluminum; an alloy material containing any of these materials as itsmain component; or the like. The thickness of the conductive layer 814can be, for example, greater than or equal to 0.1 μm and less than orequal to 3 μm, and preferably greater than or equal to 0.1 μm and lessthan or equal to 0.5 μm.

<Examples of Materials>

Next, materials and the like that can be used for a light-emitting panelare described. Note that description on the components already describedin this specification is omitted in some cases.

For each of the substrates, a material such as glass, quartz, an organicresin, a metal, or an alloy can be used. The substrate on the side fromwhich light from the light-emitting element is extracted is formed usinga material which transmits the light.

It is particularly preferable to use a flexible substrate. For example,an organic resin; a glass material, a metal, or an alloy that is thinenough to have flexibility; or the like can be used.

An organic resin, which has a specific gravity smaller than that ofglass, is preferably used for the flexible substrate, in which case thelight-emitting panel can be more lightweight compared with the casewhere glass is used.

The substrates are preferred to be formed using a material with hightoughness. In that case, a light-emitting panel with high impactresistance that is less likely to be broken can be provided. Forexample, when an organic resin substrate, a thin metal substrate, or athin alloy substrate is used, the light-emitting panel can be lighterand more robust than the case where a glass substrate is used.

A metal material and an alloy material, which have high thermalconductivity, are each preferable because they can easily conduct heatto the whole substrate and accordingly can prevent a local temperaturerise in the light-emitting panel. The thickness of a substrate using ametal material or an alloy material is preferably greater than or equalto 10 μm and less than or equal to 200 μm, and further preferablygreater than or equal to 20 μm and less than or equal to 50 μm.

There is no particular limitation on a material of the metal substrateor the alloy substrate, but it is preferable to use, for example,aluminum, copper, nickel, a metal alloy such as an aluminum alloy orstainless steel.

Furthermore, when a material with high thermal emissivity is used forthe substrate, the surface temperature of the light-emitting panel canbe prevented from rising, leading to prevention of breakage or adecrease in reliability of the light-emitting panel. For example, thesubstrate may have a stacked-layer structure of a metal substrate and alayer with high thermal emissivity (e.g., the layer can be formed usinga metal oxide or a ceramic material).

Examples of materials having flexibility and a light-transmittingproperty include a material used for the protective substrate 132described in Embodiment 1.

The flexible substrate may have a stacked-layer structure in which ahard coat layer (such as a silicon nitride layer) by which a surface ofa light-emitting device is protected from damage, a layer (such as anaramid resin layer) which can disperse pressure, or the like is stackedover a layer of any of the above-mentioned materials.

The flexible substrate may be formed by stacking a plurality of layers.When a glass layer is used, a barrier property against water or oxygencan be improved and thus a reliable light-emitting panel can beprovided.

A flexible substrate in which a glass layer, a bonding layer, and anorganic resin layer are stacked from the side closer to a light-emittingelement is preferably used. The thickness of the glass layer is greaterthan or equal to 20 μm and less than or equal to 200 μm, and preferablygreater than or equal to 25 μm and less than or equal to 100 μm. Withsuch a thickness, the glass layer can have both a high barrier propertyagainst water or oxygen and a high flexibility. The thickness of theorganic resin layer is greater than or equal to 10 μm and less than orequal to 200 μm, and preferably greater than or equal to 20 μm and lessthan or equal to 50 μm. Providing such organic resin layer can suppressoccurrence of a crack or a break in the glass layer and improvemechanical strength. With the substrate that includes such a compositematerial of a glass material and an organic resin, a highly reliable andflexible light-emitting panel can be provided.

Any of a variety of curable adhesives, e.g., light curable adhesivessuch as a UV curable adhesive, a reactive curable adhesive, a thermalcurable adhesive, and an anaerobic adhesive can be used for the bondinglayer. Examples of these adhesives include an epoxy resin, an acrylicresin, a silicone resin, a phenol resin, a polyimide resin, an imideresin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB)resin, and an ethylene vinyl acetate (EVA) resin. In particular, amaterial with low moisture permeability, such as an epoxy resin, ispreferred. Alternatively, a two-component-mixture-type resin may beused. Further alternatively, an adhesive sheet or the like may be used.

Furthermore, the resin may include a drying agent. For example, asubstance that adsorbs moisture by chemical adsorption, such as oxide ofan alkaline earth metal (e.g., calcium oxide or barium oxide), can beused. Alternatively, a substance that adsorbs moisture by physicaladsorption, such as zeolite or silica gel, may be used. The drying agentis preferably included because it can prevent an impurity such asmoisture from entering the functional element, thereby improving thereliability of the light-emitting panel.

In addition, it is preferable to mix a filler with a high refractiveindex or light-scattering member into the resin, in which case theefficiency of light extraction from the light-emitting element can beimproved. For example, titanium oxide, barium oxide, zeolite, zirconium,or the like can be used.

An insulating film with high resistance to moisture is preferably usedfor each of the insulating layer 705 and the insulating layer 715.Alternatively, each of the insulating layer 705 and the insulating layer715 preferably has a function of preventing diffusion of impurities to alight-emitting element.

As an insulating film having an excellent moisture-resistant property, afilm containing nitrogen and silicon (e.g., a silicon nitride film, asilicon nitride oxide film, or the like), a film containing nitrogen andaluminum (e.g., an aluminum nitride film or the like), or the like canbe used. Alternatively, a silicon oxide film, a silicon oxynitride film,an aluminum oxide film, or the like can be used.

For example, the moisture vapor transmission rate of the insulating filmhighly resistant to moisture is lower than or equal to 1×10⁻⁵[g/(m².day)], preferably lower than or equal to 1×10⁻⁶ [g/(m².day)],further preferably lower than or equal to 1×10⁻⁷ [g/(m².day)], and stillfurther preferably lower than or equal to 1×10⁻⁸ [g/(m².day)].

In the light-emitting panel, it is necessary that at least one of theinsulating layers 705 and 715 transmit light emitted from thelight-emitting element. One of the insulating layers 705 and 715, whichtransmits light emitted from the light-emitting element, preferably hashigher average transmittance of light having a wavelength of greaterthan or equal to 400 nm and less than or equal to 800 nm than the other.

The insulating layers 705 and 715 each preferably include oxygen,nitrogen, and silicon. The insulating layers 705 and 715 each preferablyinclude, for example, silicon oxynitride.

Moreover, the insulating layers 705 and 715 each preferably includesilicon nitride or silicon nitride oxide. It is preferable that theinsulating layers 705 and 715 be each formed using a silicon oxynitridefilm and a silicon nitride film, which are in contact with each other.The silicon oxynitride film and the silicon nitride film are alternatelystacked so that antiphase interference occurs more often in a visibleregion, whereby the stack can have higher transmittance of light in thevisible region.

There is no particular limitation on the structure of the transistor inthe light-emitting panel. For example, a forward staggered transistor oran inverted staggered transistor may be used. Furthermore, a top-gatetransistor or a bottom-gate transistor may be used. There is noparticular limitation on a semiconductor material used for thetransistors, and for example, silicon, germanium, or an organicsemiconductor can be used. Alternatively, an oxide semiconductorcontaining at least one of indium, gallium, and zinc, such as anIn—Ga—Zn-based metal oxide, may be used.

There is no particular limitation on the crystallinity of asemiconductor material used for the transistors, and an amorphoussemiconductor or a semiconductor having crystallinity (amicrocrystalline semiconductor, a poly crystalline semiconductor, asingle-crystal semiconductor, or a semiconductor partly includingcrystal regions) may be used. It is preferable that a semiconductorhaving crystallinity be used, in which case deterioration of thetransistor characteristics can be inhibited.

In one embodiment of the present invention, a c-axis aligned crystallineoxide semiconductor (CAAC-OS) is preferably used as the semiconductormaterial used for the transistors. Unlike amorphous semiconductor, theCAAC-OS has few defect states, so that the reliability of the transistorcan be improved. Moreover, since the CAAC-OS does not have a grainboundary, a stable and uniform film can be formed over a large area, andstress that is caused by bending a flexible light-emitting device doesnot easily make a crack in a CAAC-OS film.

A CAAC-OS is a crystalline oxide semiconductor having c-axis alignmentof crystals in a direction substantially perpendicular to the filmsurface. It has been found that oxide semiconductors have a variety ofcrystal structures other than a single-crystal structure. An example ofsuch structures is a nano-crystal (nc) structure, which is an aggregateof nanoscale microcrystals. The crystallinity of a CAAC-OS structure islower than that of a single-crystal structure and higher than that of annc structure.

For stable characteristics of the transistor, a base film is preferablyprovided. The base film can be formed to have a single-layer structureor a stacked-layer structure using an inorganic insulating film such asa silicon oxide film, a silicon nitride film, a silicon oxynitride film,or a silicon nitride oxide film. The base film can be formed by asputtering method, a chemical vapor deposition (CVD) method (e.g., aplasma CVD method, a thermal CVD method, or a metal organic CVD (MOCVD)method), an atomic layer deposition (ALD) method, a coating method, aprinting method, or the like. Note that the base film is not necessarilyprovided. In each of the above structure examples, the insulating layer705 can serve as a base film of the transistor.

As the light-emitting element, a self-luminous element can be used, andan element whose luminance is controlled by current or voltage isincluded in the category of the light-emitting element. For example, alight-emitting diode (LED), an organic EL element, an inorganic ELelement, or the like can be used.

The light-emitting element may have any of a top emission structure, abottom emission structure, and a dual emission structure. A conductivefilm that transmits visible light is used as the electrode through whichlight is extracted. A conductive film that reflects visible light ispreferably used as the electrode through which light is not extracted.

The conductive film that transmits visible light can be formed using,for example, indium oxide, indium tin oxide (ITO), indium zinc oxide,zinc oxide (ZnO), or zinc oxide to which gallium is added.Alternatively, a film of a metal material such as gold, silver,platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron,cobalt, copper, palladium, or titanium; an alloy containing any of thesemetal materials; a nitride of any of these metal materials (e.g.,titanium nitride); or the like can be formed thin so as to have alight-transmitting property. Alternatively, a stacked film of any of theabove materials can be used as the conductive layer. For example, astacked film of ITO and an alloy of silver and magnesium is preferablyused, in which case conductivity can be increased. Furtheralternatively, graphene or the like may be used.

For the conductive film that reflects visible light, for example, ametal material, such as aluminum, gold, platinum, silver, nickel,tungsten, chromium, molybdenum, iron, cobalt, copper, or palladium or analloy including any of these metal materials can be used. Lanthanum,neodymium, germanium, or the like may be added to the metal material orthe alloy. Furthermore, an alloy containing aluminum (an aluminum alloy)such as an alloy of aluminum and titanium, an alloy of aluminum andnickel, an alloy of aluminum and neodymium, or an alloy of aluminum,nickel, and lanthanum (Al—Ni—La), or an alloy containing silver such asan alloy of silver and copper, an alloy of silver, palladium, and copper(Ag—Pd—Cu, also referred to as APC), or an alloy of silver and magnesiumcan be used for the conductive film. An alloy of silver and copper ispreferable because of its high heat resistance. Moreover, a metal filmor a metal oxide film is stacked on an aluminum alloy film, wherebyoxidation of the aluminum alloy film can be suppressed. Examples of amaterial for the metal film or the metal oxide film are titanium andtitanium oxide. Alternatively, the conductive film having a property oftransmitting visible light and a film containing any of the above metalmaterials may be stacked. For example, a stacked film of silver and ITOor a stacked film of an alloy of silver and magnesium and ITO can beused.

The electrodes may be formed separately by an evaporation method or asputtering method. Alternatively, a discharging method such as anink-jet method, a printing method such as a screen printing method, or aplating method can be used.

When a voltage higher than the threshold voltage of the light-emittingelement is applied between the lower electrode 831 and the upperelectrode 835, holes are injected to the EL layer 833 from the anodeside and electrons are injected to the EL layer 833 from the cathodeside. The injected electrons and holes are recombined in the EL layer833 and a light-emitting substance contained in the EL layer 833 emitslight.

The EL layer 833 includes at least a light-emitting layer. In additionto the light-emitting layer, the EL layer 833 may further include one ormore layers containing any of a substance with a high hole-injectionproperty, a substance with a high hole-transport property, ahole-blocking material, a substance with a high electron-transportproperty, a substance with a high electron-injection property, asubstance with a bipolar property (a substance with a high electron- andhole-transport property), and the like.

For the EL layer 833, either a low molecular compound or a highmolecular compound can be used, and an inorganic compound may also beused. Each of the layers included in the EL layer 833 can be formed byany of the following methods: an evaporation method (including a vacuumevaporation method), a transfer method, a printing method, an inkjetmethod, a coating method, and the like.

The light-emitting element 830 may contain two or more kinds oflight-emitting substances. Thus, for example, a light-emitting elementthat emits white light can be achieved. For example, a white emissioncan be obtained by selecting light-emitting substances so that two ormore kinds of light-emitting substances emit light of complementarycolors. A light-emitting substance that emits red (R) light, green (G)light, blue (B) light, yellow (Y) light, or orange (0) light or alight-emitting substance that emits light containing spectral componentsof two or more of R light, G light, and B light can be used, forexample. A light-emitting substance that emits blue light and alight-emitting substance that emits yellow light may be used, forexample. At this time, the emission spectrum of the light-emittingsubstance that emits yellow light preferably contains spectralcomponents of G light and R light. The emission spectrum of thelight-emitting element 830 preferably has two or more peaks in thewavelength range in a visible region (e.g., greater than or equal to 350nm and less than or equal to 750 nm or greater than or equal to 400 nmand less than or equal to 800 nm).

The EL layer 833 may include a plurality of light-emitting layers. Inthe EL layer 833, the plurality of light-emitting layers may be stackedin contact with one another or may be stacked with a separation layerprovided therebetween. The separation layer may be provided between afluorescent layer and a phosphorescent layer, for example.

The separation layer can be provided, for example, to prevent energytransfer by the Dexter mechanism (particularly triplet energy transfer)from a phosphorescent material or the like in an excited state which isgenerated in the phosphorescent layer to a fluorescent material or thelike in the fluorescent layer. The thickness of the separation layer maybe several nanometers.

Specifically, the thickness of the separation layer may be greater thanor equal to 0.1 nm and less than or equal to 20 nm, greater than orequal to 1 nm and less than or equal to 10 nm, or greater than or equalto 1 nm and less than or equal to 5 nm. The separation layer contains asingle material (preferably, a bipolar substance) or a plurality ofmaterials (preferably, a hole-transport material and anelectron-transport material).

The separation layer may be formed using a material contained in alight-emitting layer in contact with the separation layer. Thisfacilitates the manufacture of the light-emitting element and reducesthe drive voltage. For example, in the case where the phosphorescentlayer includes a host material, an assist material, and a phosphorescentmaterial (guest material), the separation layer may be formed using thehost material and the assist material. In other words, the separationlayer includes a region not containing the phosphorescent material andthe phosphorescent layer includes a region containing the phosphorescentmaterial in the above structure. Accordingly, the separation layer andthe phosphorescent layer can be evaporated separately depending onwhether a phosphorescent material is used or not. With such a structure,the separation layer and the phosphorescent layer can be formed in thesame chamber. Thus, the manufacturing costs can be reduced.

Moreover, the light-emitting element 830 may be a single elementincluding one EL layer or a tandem element in which EL layers arestacked with a charge generation layer provided therebetween.

The light-emitting element is preferably provided between a pair ofinsulating films having an excellent moisture-resistant property. Inthat case, entry of an impurity such as moisture into the light-emittingelement can be inhibited, leading to inhibition of a decrease in thereliability of the light-emitting device. Specifically, the use of aninsulating film having high resistance to moisture for the insulatinglayer 705 and the insulating layer 715 allows the light-emitting elementto be located between a pair of insulating films having high resistanceto moisture, by which decrease in reliability of the light-emittingdevice can be prevented.

As the insulating layer 815, for example, an inorganic insulating filmsuch as a silicon oxide film, a silicon oxynitride film, or an aluminumoxide film can be used. For example, as the insulating layer 817, theinsulating layer 817 a, and the insulating layer 817 b, an organicmaterial such as polyimide, acrylic, polyamide, polyimide amide, or abenzocyclobutene-based resin can be used. Alternatively, alow-dielectric constant material (a low-k material) or the like can beused. Furthermore, each insulating layer may be formed by stacking aplurality of insulating films.

The insulating layer 821 is formed using an organic insulating materialor an inorganic insulating material. As the resin, for example, apolyimide resin, a polyamide resin, an acrylic resin, a siloxane resin,an epoxy resin, or a phenol resin can be used. It is particularlypreferable that the insulating layer 821 be formed using aphotosensitive resin material and an opening portion be formed over thelower electrode 831 so that a side wall of the opening portion is formedas an inclined surface with a continuous curvature.

There is no particular limitation on the method for forming theinsulating layer 821. A photolithography method, a sputtering method, anevaporation method, a droplet discharging method (e.g., an inkjetmethod), a printing method (e.g., a screen printing method or an off-setprinting method) can be used, for example.

The spacer 823 can be formed using an inorganic insulating material, anorganic insulating material, a metal material, or the like. As theinorganic insulating material or the organic insulating material, forexample, a variety of materials that can be used for the insulatinglayer can be used. As the metal material, titanium, aluminum, or thelike can be used. When the spacer 823 containing a conductive materialis electrically connected to the upper electrode 835, a potential dropdue to the resistance of the upper electrode 835 can be inhibited. Thespacer 823 may have either a tapered shape or an inverse tapered shape.

For example, a conductive layer functioning as an electrode or a wiringof the transistor, an auxiliary electrode of the light-emitting element,or the like, which is used for the light-emitting device, can be formedto have a single-layer structure or a stacked-layer structure using anyof metal materials such as molybdenum, titanium, chromium, tantalum,tungsten, aluminum, copper, neodymium, and scandium, and an alloymaterial containing any of these elements. Alternatively, the conductivelayer may be formed using a conductive metal oxide. As the conductivemetal oxide, indium oxide (e.g., In₂O₃), tin oxide (e.g., SnO₂), ZnO,ITO, indium zinc oxide (e.g., In₂O₃—ZnO), or any of these metal oxidematerials in which silicon oxide is contained can be used.

The coloring layer is a colored layer that transmits light in a specificwavelength range. For example, a color filter for transmitting light ina red, green, blue, or yellow wavelength range can be used. Eachcoloring layer is formed in a desired position with any of variousmaterials by a printing method, an inkjet method, an etching methodusing a photolithography method, or the like. In a white sub-pixel, aresin such as a transparent resin may be provided so as to overlap withthe light-emitting element.

The light-blocking layer is provided between the adjacent coloringlayers. The light-blocking layer blocks light emitted from an adjacentlight-emitting element to inhibit color mixture between adjacentlight-emitting elements. Here, the coloring layer is provided such thatits end portion overlaps with the light-blocking layer, whereby lightleakage can be reduced. As the light-blocking layer, a material that canblock light from the light-emitting element can be used; for example, ablack matrix is formed using a resin material containing a metalmaterial, pigment, or dye. Note that it is preferable to provide thelight-blocking layer in a region other than the light-emitting portion,such as a driver circuit portion, in which case undesired leakage ofguided light or the like can be inhibited.

Furthermore, an overcoat covering the coloring layer and thelight-blocking layer may be provided. The overcoat can prevent animpurity and the like contained in the coloring layer from beingdiffused into the light-emitting element. The overcoat is formed with amaterial that transmits light emitted from the light-emitting element;for example, an inorganic insulating film such as a silicon nitride filmor a silicon oxide film, an organic insulating film such as an acrylicfilm or a polyimide film can be used, and a stacked-layer structure ofan organic insulating film and an inorganic insulating film may beemployed.

In the case where upper surfaces of the coloring layer and thelight-blocking layer are coated with a material of the bonding layer, amaterial which has high wettability with respect to the material of thebonding layer is preferably used as the material of the overcoat. Forexample, an oxide conductive film such as an ITO film or a metal filmsuch as an Ag film which is thin enough to transmit light is preferablyused as the overcoat.

As the connector, any of a variety of anisotropic conductive films(ACF), anisotropic conductive pastes (ACP), and the like can be used.

As described above, a variety of panels such as a light-emitting panel,a display panel, and a touch panel can be used in the display system ofone embodiment of the present invention.

Examples of the display element include an EL element (an EL elementcontaining organic and inorganic materials, an organic EL element, or aninorganic EL element), an LED (a white LED, a red LED, a green LED, ablue LED, or the like), a liquid crystal element, an electrophoreticelement, and a display element using a micro electro mechanical systems(MEMS).

Note that the light-emitting panel of one embodiment of the presentinvention may be used as a display device or as a lighting panel. Forexample, it may be used as a light source such as a backlight or a frontlight, that is, a lighting device for a display panel.

As described above, with an image processing device and thelight-emitting panel including a region that transmits visible lightdescribed in this embodiment, a large display system in which a seambetween light-emitting panels is hardly recognized and displayunevenness is suppressed can be obtained.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 3

In this embodiment, a flexible display panel, which is an example of adisplay panel that can be used for the display system of one embodimentof the present invention, will be described with reference to drawings.Note that the above description can be referred to for the components ofa touch panel, which are similar to those of the light-emitting paneldescribed in Embodiment 2. Although a touch panel including alight-emitting element is described in this embodiment as an example,one embodiment of the present invention is not limited to this example.

Structure Example 1

FIG. 21A is a top view of the touch panel. FIG. 21B is a cross-sectionalview taken along dashed-dotted line A-B and dashed-dotted line C-D inFIG. 21A. FIG. 21C is a cross-sectional view taken along dashed-dottedline E-F in FIG. 21A.

A touch panel 390 illustrated in FIG. 21A includes a display portion 301(serving also as an input portion), a scan line driver circuit 303 g(1),an imaging pixel driver circuit 303 g(2), an image signal line drivercircuit 303 s(1), and an imaging signal line driver circuit 303 s(2).

The display portion 301 includes a plurality of pixels 302 and aplurality of imaging pixels 308.

The pixel 302 includes a plurality of sub-pixels. Each sub-pixelincludes a light-emitting element and a pixel circuit.

The pixel circuits can supply electric power for driving thelight-emitting element. The pixel circuits are electrically connected towirings through which selection signals are supplied. The pixel circuitsare also electrically connected to wirings through which image signalsare supplied.

The scan line driver circuit 303 g(1) can supply selection signals tothe pixels 302.

The image signal line driver circuit 303 s(1) can supply image signalsto the pixels 302.

A touch sensor can be formed using the imaging pixels 308. Specifically,the imaging pixels 308 can sense a touch of a finger or the like on thedisplay portion 301.

The imaging pixels 308 include photoelectric conversion elements andimaging pixel circuits.

The imaging pixel circuits can drive photoelectric conversion elements.The imaging pixel circuits are electrically connected to wirings throughwhich control signals are supplied. The imaging pixel circuits are alsoelectrically connected to wirings through which power supply potentialsare supplied.

Examples of the control signal include a signal for selecting an imagingpixel circuit from which a recorded imaging signal is read, a signal forinitializing an imaging pixel circuit, and a signal for determining thetime for an imaging pixel circuit to sense light.

The imaging pixel driver circuit 303 g(2) can supply control signals tothe imaging pixels 308.

The imaging signal line driver circuit 303 s(2) can read out imagingsignals.

As illustrated in FIGS. 21B and 21C, the touch panel 390 includes thesubstrate 701, the bonding layer 703, the insulating layer 705, thesubstrate 711, the bonding layer 713, and the insulating layer 715. Thesubstrates 701 and 711 are bonded to each other with a bonding layer360.

The substrate 701 and the insulating layer 705 are attached to eachother with the bonding layer 703. The substrate 711 and the insulatinglayer 715 are attached to each other with the bonding layer 713.

Embodiment 2 can be referred to for materials used for the substrates,the bonding layers, and the insulating layers.

Each of the pixels 302 includes the sub-pixel 302R, a sub-pixel 302G,and a sub-pixel 302B (FIG. 21C).

For example, the sub-pixel 302R includes the light-emitting element 350Rand the pixel circuit. The pixel circuit includes a transistor 302 tthat can supply electric power to the light-emitting element 350R. Thesub-pixel 302R further includes an optical element (e.g., a coloringlayer 367R that transmits red light).

The light-emitting element 350R includes a lower electrode 351R, an ELlayer 353, and an upper electrode 352, which are stacked in this order(see FIG. 21C).

The EL layer 353 includes a first EL layer 353 a, an intermediate layer354, and a second EL layer 353 b, which are stacked in this order.

Note that a microcavity structure can be provided for the light-emittingelement 350R so that light with a specific wavelength can be efficientlyextracted. Specifically, an EL layer may be provided between a film thatreflects visible light and a film that partly reflects and partlytransmits visible light, which are provided so that light with aspecific wavelength can be efficiently extracted.

The sub-pixel 302R includes, for example, a bonding layer 360 that is incontact with the light-emitting element 350R and the coloring layer367R.

The coloring layer 367R is positioned in a region overlapping with thelight-emitting element 350R. Accordingly, part of light emitted from thelight-emitting element 350R passes through the bonding layer 360 andthrough the coloring layer 367R and is emitted to the outside of thesub-pixel 302R as indicated by an arrow in FIG. 21C.

The touch panel 390 includes a light-blocking layer 367BM. Thelight-blocking layer 367BM is provided so as to surround the coloringlayer (e.g., the coloring layer 367R).

The touch panel 390 includes an anti-reflective layer 367 p positionedin a region overlapping with the display portion 301. As theanti-reflective layer 367 p, a circular polarizing plate can be used,for example.

The touch panel 390 includes an insulating layer 321. The insulatinglayer 321 covers the transistor 302 t and the like. Note that theinsulating layer 321 can be used as a layer for covering unevennesscaused by the pixel circuit or the imaging pixel circuit to provide aflat surface. The transistor 302 t and the like are preferably coveredwith an insulating layer that can inhibit diffusion of impurities to thetransistor 302 t and the like.

The touch panel 390 includes a partition 328 that overlaps with an endportion of the lower electrode 351R. A spacer 329 that controls thedistance between the substrate 701 and the substrate 711 is provided onthe partition 328.

The image signal line driver circuit 303 s(1) includes a transistor 303t and a capacitor 303 c. Note that the driver circuit can be formed inthe same process and over the same substrate as those of the pixelcircuits. As illustrated in FIG. 21B, the transistor 303 t may include asecond gate 304 over the insulating layer 321. The second gate 304 maybe electrically connected to a gate of the transistor 303 t, ordifferent potentials may be supplied to these gates. Alternatively, ifnecessary, the second gate 304 may be provided for a transistor 308 t,the transistor 302 t, or the like.

The imaging pixels 308 each include a photoelectric conversion element308 p and an imaging pixel circuit. The imaging pixel circuit can senselight received by the photoelectric conversion element 308 p. Theimaging pixel circuit includes the transistor 308 t.

For example, a PIN photodiode can be used as the photoelectricconversion element 308 p.

The touch panel 390 includes a wiring 311 through which a signal issupplied. The wiring 311 is provided with a terminal 319. An FPC 309through which a signal such as an image signal or a synchronizationsignal is supplied is electrically connected to the terminal 319. Aprinted wiring board (PWB) may be attached to the FPC 309.

Note that transistors such as the transistors 302 t, 303 t, and 308 tcan be formed in the same process. Alternatively, the transistors may beformed in different processes.

Structure Example 2

FIGS. 22A and 22B are perspective views of a touch panel 505. FIGS. 22Aand 22B illustrate only main components for simplicity. FIGS. 23A to 23Care each a cross-sectional view taken along the dashed-dotted line X1-X2in FIG. 22A.

As illustrated in FIGS. 22A and 22B, the touch panel 505 includes adisplay portion 501, the scan line driver circuit 303 g(1), a touchsensor 595, and the like. Furthermore, the touch panel 505 includes thesubstrate 701, the substrate 711, and a substrate 590.

The touch panel 505 includes a plurality of pixels and a plurality ofwirings 311. The plurality of wirings 311 can supply signals to thepixels. The plurality of wirings 311 are arranged to a peripheralportion of the substrate 701, and part of the plurality of wirings 311form the terminal 319. The terminal 319 is electrically connected to anFPC 509(1).

The touch panel 505 includes the touch sensor 595 and a plurality ofwirings 598. The plurality of wirings 598 are electrically connected tothe touch sensor 595. The plurality of wirings 598 are arranged to aperipheral portion of the substrate 590, and part of the plurality ofwirings 598 form a terminal. The terminal is electrically connected toan FPC 509(2). Note that in FIG. 22B, electrodes, wirings, and the likeof the touch sensor 595 provided on the back side of the substrate 590(the side facing the substrate 701) are indicated by solid lines forclarity.

As the touch sensor 595, for example, a capacitive touch sensor can beused. Examples of the capacitive touch sensor include a surfacecapacitive touch sensor and a projected capacitive touch sensor. Anexample of using a projected capacitive touch sensor is described here.

Examples of the projected capacitive touch sensor include aself-capacitive touch sensor and a mutual capacitive touch sensor. Theuse of a mutual capacitive type is preferable because multiple pointscan be sensed simultaneously.

Note that a variety of sensors that can sense the closeness or thecontact of a sensing target such as a finger can be used as the touchsensor 595.

The projected capacitive touch sensor 595 includes electrodes 591 andelectrodes 592. The electrodes 591 are electrically connected to any ofthe plurality of wirings 598, and the electrodes 592 are electricallyconnected to any of the other wirings 598.

The electrodes 592 each have a shape of a plurality of quadranglesarranged in one direction with one corner of a quadrangle connected toone corner of another quadrangle as illustrated in FIGS. 22A and 22B.

The electrodes 591, each of which has a quadrangular shape, are arrangedin a direction intersecting with the direction in which the electrodes592 extend. Note that the plurality of electrodes 591 is not necessarilyarranged in the direction orthogonal to one electrode 592 and may bearranged in a direction that intersects with one electrode 592 at anangle of less than 90 degrees.

The wiring 594 intersects with the electrode 592. One wiring 594electrically connects two electrodes 591 between which one electrode 592is positioned. The intersecting area of the electrode 592 and the wiring594 is preferably as small as possible. Such a structure allows areduction in the area of a region where the electrodes are not provided,reducing unevenness in transmittance. As a result, unevenness inluminance of light from the touch sensor 595 can be reduced.

Note that the shapes of the electrodes 591 and the electrodes 592 arenot limited to the above-mentioned shapes and can be any of a variety ofshapes. For example, the plurality of electrodes 591 may be provided sothat space between the electrodes 591 are reduced as much as possible,and a plurality of electrodes 592 may be provided with an insulatinglayer sandwiched between the electrodes 591 and the electrodes 592 andmay be spaced apart from each other to form a region not overlappingwith the electrodes 591. In that case, between two adjacent electrodes592, it is preferable to provide a dummy electrode which is electricallyinsulated from these electrodes, whereby the area of a region having adifferent transmittance can be reduced.

As illustrated in FIG. 23A, the touch panel 505 includes the substrate701, the bonding layer 703, the insulating layer 705, the substrate 711,the bonding layer 713, and the insulating layer 715. The substrates 701and 711 are bonded to each other with a bonding layer 360.

A bonding layer 597 attaches the substrate 590 to the substrate 711 sothat the touch sensor 595 overlaps with the display portion 501. Thebonding layer 597 has a light-transmitting property.

The electrodes 591 and the electrodes 592 are formed using alight-transmitting conductive material. As a light-transmittingconductive material, a conductive oxide such as indium oxide, indium tinoxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium isadded can be used. A film including graphene may be used as well. Thefilm including graphene can be formed, for example, by reducing a filmincluding graphene oxide. As a reducing method, heating or the like canbe employed.

The resistance of conductive films such as the electrodes 591, theelectrodes 592, and the wiring 594, which are materials used for wiringsand electrodes in the touch panel, is preferably low. Examples of thematerial include ITO, indium zinc oxide, ZnO, silver, copper, aluminum,a carbon nanotube, and graphene. Alternatively, a metal nanowireincluding a number of conductors with an extremely small width (forexample, a diameter of several nanometers) may be used. Examples of sucha metal nanowire include an Ag nanowire, a Cu nanowire, and an Alnanowire.

In the case of using an Ag nanowire, light transmittance of 89% or moreand a sheet resistance of 40 ohm/square or more and 100 ohm/square orless can be achieved. Note that a metal nanowire, a carbon nanotube,graphene, or the like may be used for an electrode of the displayelement, e.g., a pixel electrode or a common electrode because of itshigh transmittance.

The electrodes 591 and the electrodes 592 may be formed by depositing alight-transmitting conductive material on the substrate 590 by asputtering method and then removing an unnecessary portion by a varietyof patterning technique such as photolithography.

The electrodes 591 and the electrodes 592 are covered with an insulatinglayer 593. Furthermore, openings reaching the electrodes 591 are formedin the insulating layer 593, and the wiring 594 electrically connectsthe adjacent electrodes 591. A light-transmitting conductive materialcan be favorably used as the wiring 594 because the aperture ratio ofthe touch panel can be increased. Moreover, a material with higherconductivity than the conductivities of the electrodes 591 and 592 canbe favorably used as the wiring 594 because electric resistance can bereduced.

Note that an insulating layer that covers the insulating layer 593 andthe wiring 594 may be provided to protect the touch sensor 595.

Furthermore, a connection layer 599 electrically connects the wiring 598to the FPC 509(2).

The display portion 501 includes a plurality of pixels arranged in amatrix. Each pixel has the same structure as Structure Example 1; thus,description is omitted.

Any of various kinds of transistors can be used in the touch panel. Astructure in the case of using bottom-gate transistors is illustrated inFIGS. 23A and 23B.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 302 t andthe transistor 303 t illustrated in FIG. 23A.

For example, a semiconductor layer containing polycrystalline siliconthat is obtained by crystallization process such as laser annealing canbe used in the transistor 302 t and the transistor 303 t illustrated inFIG. 23B.

A structure in the case of using top-gate transistors is illustrated inFIG. 23C.

For example, a semiconductor layer containing polycrystalline silicon, asingle crystal silicon film that is transferred from a single crystalsilicon substrate, or the like can be used in the transistor 302 t andthe transistor 303 t illustrated in FIG. 23C.

Structure Example 3

FIGS. 24A to 24C are cross-sectional views of a touch panel 505B. Thetouch panel 505B described in this embodiment is different from thetouch panel 505 in Structure Example 2 in that an image is displayed onthe side where the transistors are provided and that the touch sensor isprovided on the substrate 701 side of the display portion. Differentstructures will be described in detail below, and the above descriptionis referred to for the other similar structures.

The coloring layer 367R is positioned in a region overlapping with thelight-emitting element 350R. The light-emitting element 350R illustratedin FIG. 24A emits light to the side where the transistor 302 t isprovided. Accordingly, part of light emitted from the light-emittingelement 350R passes through the coloring layer 367R and is emitted tothe outside of the touch panel 505B as indicated by an arrow in FIG.24A.

The touch panel 505B includes the light-blocking layer 367BM on thelight extraction side.

The light-blocking layer 367BM is provided so as to surround thecoloring layer (e.g., the coloring layer 367R).

The touch sensor 595 is provided not on the substrate 711 side but onthe substrate 701 side (see FIG. 24A).

The bonding layer 597 attaches the substrate 590 to the substrate 701 sothat the touch sensor 595 overlaps with the display portion. The bondinglayer 597 has a light-transmitting property.

Note that a structure in the case of using bottom-gate transistors inthe display portion 501 is illustrated in FIGS. 24A and 24B.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 302 t andthe transistor 303 t illustrated in FIG. 24A.

For example, a semiconductor layer containing polycrystalline siliconcan be used in the transistor 302 t and the transistor 303 t illustratedin FIG. 24B.

A structure in the case of using top-gate transistors is illustrated inFIG. 24C.

For example, a semiconductor layer containing polycrystalline silicon, asingle crystal silicon film that is transferred from a single crystalsilicon substrate, or the like can be used in the transistor 302 t andthe transistor 303 t illustrated in FIG. 24C.

Structure Example 4

As illustrated in FIG. 25, the touch panel 500TP includes a displayportion 500 and an input portion 600 that overlap with each other. FIG.26 is a cross-sectional view taken along the dashed-dotted line Z1-Z2 inFIG. 25.

Components of the touch panel 500TP are described below. Note that theseunits cannot be clearly distinguished and one unit also serves asanother unit or include part of another unit in some cases. Note thatthe touch panel 500TP in which the input portion 600 overlaps with thedisplay portion 500 is also referred to as a touch panel.

The input portion 600 includes a plurality of sensing units 602 arrangedin a matrix. The input portion 600 also includes a selection signal lineG1, a control line RES, a signal line DL, and the like.

The selection signal line G1 and the control line RES are electricallyconnected to the plurality of sensing units 602 that are arranged in therow direction (indicated by the arrow R in FIG. 25). The signal line DLis electrically connected to the plurality of sensing units 602 that arearranged in the column direction (indicated by the arrow C in FIG. 25).

The sensing unit 602 senses an object that is close thereto or incontact therewith and supplies a sensing signal. For example, thesensing unit 602 senses, for example, capacitance, illuminance, magneticforce, electric waves, or pressure and supplies data based on the sensedphysical quantity. Specifically, a capacitor, a photoelectric conversionelement, a magnetic sensing element, a piezoelectric element, aresonator, or the like can be used as the sensing element.

The sensing unit 602 senses, for example, a change in capacitancebetween the sensing unit 602 and an object close thereto or an object incontact therewith.

Note that when an object having a dielectric constant higher than thatof air, such as a finger, comes close to a conductive film in air, thecapacitance between the finger and the conductive film changes. Thesensing unit 602 can sense the capacitance change and supply sensingdata.

For example, distribution of charge occurs between the conductive filmand the capacitor owing to the change in the electrostatic capacitance,so that the voltage across the capacitor is changed. This voltage changecan be used as the sensing signal.

The sensing unit 602 is provided with a sensor circuit. The sensorcircuit is electrically connected to the selection signal line G1, thecontrol line RES, the signal line DL, or the like.

The sensor circuit includes a transistor, a sensor element, and thelike. For example, a conductive film and a capacitor electricallyconnected to the conductive film can be used for the sensor circuit. Acapacitor and a transistor electrically connected to the capacitor canalso be used for the sensor circuit.

For example, a capacitor 650 including an insulating layer 653, and afirst electrode 651 and a second electrode 652 between which theinsulating layer 653 is provided can be used for the sensor circuit (seeFIG. 26). Specifically, the voltage between the electrodes of thecapacitor 650 changes when an object approaches the conductive filmwhich is electrically connected to one electrode of the capacitor 650.

The sensing unit 602 includes a switch that can be turned on or off inaccordance with a control signal. For example, a transistor M12 can beused as the switch.

A transistor which amplifies a sensing signal can be used in the sensingunit 602.

Transistors manufactured through the same process can be used as thetransistor that amplifies a sensing signal and the switch. This allowsthe input portion 600 to be provided through a simplified process.

The sensing unit includes a plurality of window portions 667 arranged ina matrix. The window portions 667 transmit visible light. Alight-blocking layer BM may be provided between the window portions 667.

The touch panel 500TP is provided in a position overlapping with thewindow portion 667. The coloring layer transmits light of apredetermined color. Note that the coloring layer can be referred to asa color filter. For example, a coloring layer 367B transmitting bluelight, a coloring layer 367G transmitting green light, and a coloringlayer 367R transmitting red light can be used. Alternatively, a coloringlayer transmitting yellow light or white light may be used.

The display portion 500 includes the plurality of pixels 302 arranged ina matrix. The pixel 302 is positioned so as to overlap with the windowportions 667 of the input portion 600. The pixels 302 may be arranged athigher resolution than the sensing units 602. Each pixel has the samestructure as Structure Example 1; thus, description is omitted.

The touch panel 500TP includes the input portion 600 that includes theplurality of sensing units 602 arranged in a matrix and the windowportions 667 transmitting visible light, the display portion 500 thatincludes the plurality of pixels 302 overlapping with the windowportions 667, and the coloring layers between the window portions 667and the pixels 302. Each of the sensing units includes a switch that canreduce interference in another sensing unit.

Thus, sensing data obtained by each sensor unit can be supplied togetherwith the positional information of the sensor unit. In addition, sensingdata can be supplied in relation to the positional data of the pixel fordisplaying an image. In addition, the sensor unit which does not supplythe sensing data is not electrically connected to a signal line, wherebyinterference with the sensor unit which supplies a sensing signal can bereduced. Consequently, the touch panel 500TP that is highly convenientor highly reliable can be provided.

For example, the input portion 600 of the touch panel 500TP can sensesensing data and supply the sensing data together with the positionaldata. Specifically, a user of the touch panel 500TP can make a varietyof gestures (e.g., tap, drag, swipe, and pinch-in operation) using, as apointer, his/her finger or the like on the input portion 600.

The input portion 600 can sense a finger or the like that comes close toor is in contact with the input portion 600 and supply sensing dataincluding a sensed position, path, or the like.

An arithmetic unit determines whether or not supplied data satisfies apredetermined condition on the basis of a program or the like andexecutes an instruction associated with a predetermined gesture.

Thus, a user of the input portion 600 can make the predetermined gesturewith his/her finger or the like and make the arithmetic unit execute aninstruction associated with the predetermined gesture.

For example, first, the input portion 600 of the touch panel 500TPselects one sensing unit X from the plurality of sensing units that cansupply sensing data to one signal line. Then, electrical continuitybetween the signal line and the sensing units other than the sensingunit X is not established. This can reduce interference of the othersensing units in the sensing unit X.

Specifically, interference of sensing elements of the other sensingunits in a sensing element of the sensing unit X can be reduced.

For example, in the case where a capacitor and a conductive film towhich one electrode of the capacitor is electrically connected are usedfor the sensing element, interference of the potentials of theconductive films of the other sensing units in the potential of theconductive film of the sensing unit X can be reduced.

Thus, the touch panel 500TP can drive the sensing unit and supplysensing data independently of its size. The touch panel 500TP can have avariety of sizes, for example, ranging from a size for a hand-helddevice to a size for an electronic blackboard.

The touch panel 500TP can be folded and unfolded. Even in the case whereinterference of the other sensing units in the sensing unit X isdifferent between the folded state and the unfolded state, the sensingunit can be driven and sensing data can be supplied without dependenceon the state of the touch panel 500TP.

The display portion 500 of the touch panel 500TP can be supplied withdisplay data. For example, an arithmetic unit can supply the displaydata.

In addition to the above structure, the touch panel 500TP can have thefollowing structure.

The touch panel 500TP may include a driver circuit 603 g or a drivercircuit 603 d. In addition, the touch panel 500TP may be electricallyconnected to an FPC1.

The driver circuit 603 g can supply selection signals at predeterminedtimings, for example.

Specifically, the driver circuit 603 g supplies selection signals to theselection signal lines G1 row by row in a predetermined order. Any of avariety of circuits can be used as the driver circuit 603 g. Forexample, a shift register, a flip-flop circuit, a combination circuit,or the like can be used.

The driver circuit 603 d supplies sensing data on the basis of a sensingsignal supplied from the sensing unit 602. Any of a variety of circuitscan be used as the driver circuit 603 d. For example, a circuit that canform a source follower circuit or a current mirror circuit by beingelectrically connected to the sensing circuit in the sensing unit can beused as the driver circuit 603 d. In addition, an analog-to-digitalconverter circuit that converts a sensing signal into a digital signalmay be provided in the driver circuit 603 d.

The FPC1 supplies a timing signal, a power supply potential, or the likeand is supplied with a sensing signal.

The touch panel 500TP may include a driver circuit 503 g, a drivercircuit 503 s, a wiring 311, and a terminal 319. In addition, the touchpanel 500TP (or driver circuit) may be electrically connected to anFPC2.

In addition, a protective layer 670 that prevents damage and protectsthe touch panel 500TP may be provided. For example, a ceramic coat layeror a hard coat layer can be used as the protective layer 670.Specifically, a layer containing aluminum oxide or a UV curable resincan be used.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 4

In this embodiment, electronic devices and lighting devices of oneembodiment of the present invention will be described with reference todrawings.

Examples of electronic devices include a television set, a monitor of acomputer or the like, a digital camera, a digital video camera, adigital photo frame, a mobile phone (also referred to as a mobile phonedevice), a portable game machine, a portable information terminal, anaudio reproducing device, a large game machine such as a pinballmachine, and the like.

The electronic device or the lighting device of one embodiment of thepresent invention has flexibility and therefore can be incorporatedalong a curved inside/outside wall surface of a house or a building or acurved interior/exterior surface of a car.

Furthermore, the electronic device of one embodiment of the presentinvention may include a secondary battery. It is preferable that thesecondary battery be capable of being charged by non-contact powertransmission.

Examples of the secondary battery include a lithium ion secondarybattery such as a lithium polymer battery using a gel electrolyte(lithium ion polymer battery), a nickel-hydride battery, anickel-cadmium battery, an organic radical battery, a lead-acid battery,an air secondary battery, a nickel-zinc battery, and a silver-zincbattery.

The electronic device of one embodiment of the present invention mayinclude an antenna. When a signal is received by the antenna, theelectronic device can display an image, data, or the like on a displayportion. When the electronic device includes the antenna and a secondarybattery, the antenna may be used for contactless power transmission.

In the display system of one embodiment of the present invention, thearea of the display region can be increased unlimitedly by increasingthe number of display panels. Thus, the display system of one embodimentof the present invention can be favorably used for digital signage, aPID, or the like. Furthermore, the shape of the display region of thedisplay system of one embodiment of the present invention can be changedvariously when the arrangement of the display panels is changed. Inaddition, the image processing device of one embodiment of the presentinvention can make a joint between the display panels to be hardlyrecognized. Accordingly, the display unevenness or luminance unevennessof the display region can be suppressed.

FIG. 27A illustrates an example in which the display system 10 of oneembodiment of the present invention is provided for each of pillars 15and walls 16. A flexible display panel is used as a display panelincluded in the display system 10, whereby the display system 10 can beplaced along a curved surface.

Here, in particular, in the case where the display system of oneembodiment of the present invention is used in digital signage or a PID,it is preferable to use a touch panel in a display panel because adevice with such a structure does not just display a still or movingimage, but can be operated by viewers intuitively. Alternatively, in thecase where the display device of one embodiment of the present inventionis used for providing information such as route information or trafficinformation, usability can be enhanced by intuitive operation. In thecase of providing the display device on the walls of buildings, publicfacilities, or the like, a touch panel does not need to be used in thedisplay panel.

FIGS. 27B to 27E illustrate an example of an electronic device includingthe display portion 7000 with a curved surface. The display surface ofthe display portion 7000 is bent, and images can be displayed on thebent display surface. The display portion 7000 may be flexible.

The display portion 7000 of each of the electronic devices illustratedin FIGS. 27B to 27E can be formed using the display system of oneembodiment of the present invention.

FIG. 27B illustrates an example of a mobile phone. A mobile phone 7100includes a housing 7101, the display portion 7000, operation buttons7103, an external connection port 7104, a speaker 7105, a microphone7106, and the like.

The mobile phone 7100 illustrated in FIG. 27B includes a touch sensor inthe display portion 7000. Moreover, operations such as making a call andinputting a letter can be performed by touch on the display portion 7000with a finger, a stylus, or the like.

With the operation buttons 7103, power on or off can be switched.Alternatively, types of images displayed on the display portion 7000 canbe switched; switching images from a mail creation screen to a main menuscreen, for example.

FIG. 27C illustrates an example of a television set. In a television set7200, the display portion 7000 is incorporated into the housing 7201.Here, the housing 7201 is supported by a stand 7203.

The television set 7200 illustrated in FIG. 27C can be operated with anoperation switch of the housing 7201 or a separate remote controller7211. Furthermore, the display portion 7000 may include a touch sensor.The display portion 7000 can be performed by touching the displayportion with a finger or the like. Furthermore, the remote controller7211 may be provided with a display portion for displaying data outputfrom the remote controller 7211. With operation keys or a touch panel ofthe remote controller 7211, channels and volume can be controlled andimages displayed on the display portion 7000 can be controlled.

Note that the television set 7200 is provided with a receiver, a modem,or the like. A general television broadcast can be received with thereceiver. Furthermore, when the television set is connected to acommunication network with or without wires via the modem, one-way (froma transmitter to a receiver) or two-way (between a transmitter and areceiver or between receivers) data communication can be performed.

FIG. 27D illustrates an example of a portable information terminal. Aportable information terminal 7300 includes a housing 7301 and thedisplay portion 7000. Each of the portable information terminals mayalso include an operation button, an external connection port, aspeaker, a microphone, an antenna, a battery, or the like. The displayportion 7000 is provided with a touch sensor. An operation of theportable information terminal 7300 can be performed by touching thedisplay portion 7000 with a finger, a stylus, or the like.

FIG. 27D is a perspective view of the portable information terminal7300. FIG. 27E is a top view of the portable information terminal 7300.

Each of the portable information terminals illustrated in thisembodiment functions as, for example, one or more of a telephone set, anotebook, and an information browsing system. Specifically, each of theportable information terminals can be used as a smartphone. Each of theportable information terminals illustrated in this embodiment is capableof executing a variety of applications such as mobile phone calls,e-mailing, reading and editing texts, music reproduction, Internetcommunication, and a computer game, for example.

The portable information terminal 7300 can display characters or animage on its plurality of surfaces. For example, as illustrated in FIG.27D, three operation buttons 7302 can be displayed on one surface, andinformation 7303 indicated by a rectangle can be displayed on anothersurface. FIGS. 27D and 27E illustrate an example in which information isdisplayed at the top of the portable information terminal.Alternatively, information may be displayed on the side of the portableinformation terminal. Information may also be displayed on three or moresurfaces of the portable information terminal.

Examples of the information include notification from a socialnetworking service (SNS), display indicating reception of an e-mail oran incoming call, the title of an e-mail or the like, the sender of ane-mail or the like, the date, the time, remaining battery, and thereception strength of an antenna. Alternatively, the operation button,an icon, or the like may be displayed in place of the information.

For example, a user of the portable information terminal 7300 can seethe display (here, the information 7303) with the portable informationterminal 7300 put in a breast pocket of his/her clothes.

Specifically, a caller's phone number, name, or the like of an incomingcall is displayed in a position that can be seen from above the portableinformation terminal 7300. Thus, the user can see the display withouttaking out the portable information terminal 7300 from the pocket anddecide whether to answer the call.

FIG. 27F illustrates an example of a lighting device having a curvedlight-emitting portion.

The light-emitting portion included in the lighting devices illustratedin FIG. 27F can be manufactured using the display system of oneembodiment of the present invention.

A lighting device 7400 illustrated in FIG. 27F includes a light-emittingportion 7402 having a wave-shaped light-emitting surface, which is agood-design lighting device.

The light-emitting portion included in the lighting device 7400 may beflexible. The light-emitting portion may be fixed on a plastic member, amovable frame, or the like so that an emission surface of thelight-emitting portion can be bent freely depending on the intended use.

The lighting device 7400 includes a stage 7401 provided with anoperation switch 7403 and a light-emitting portion supported by thestage 7401.

Note that although the lighting device in which the light-emittingportion is supported by the stage is described as an example here, ahousing provided with a light-emitting portion can be fixed on a ceilingor suspended from a ceiling. Since the light-emitting surface can becurved, the light-emitting surface is curved to have a depressed shape,whereby a particular region can be brightly illuminated, or thelight-emitting surface is curved to have a projecting shape, whereby awhole room can be brightly illuminated.

FIGS. 28A1, 28A2, and 28B to 281 each illustrate an example of aportable information terminal including a display portion 7001 havingflexibility.

The display portion 7001 is manufactured using the display system of oneembodiment of the present invention. For example, a display systemincluding a display panel that can be bent with a radius of curvature ofgreater than or equal to 0.01 mm and less than or equal to 150 mm can beused. The display portion 7001 may include a touch sensor so that theportable information terminal can be operated by touching the displayportion 7001 with a finger or the like.

FIGS. 28A1 and 28A2 are a perspective view and a side view,respectively, illustrating an example of the portable informationterminal. A portable information terminal 7500 includes a housing 7501,the display portion 7001, a display portion tab 7502, operation buttons7503, and the like.

The portable information terminal 7500 includes a rolled flexibledisplay portion 7001 in the housing 7501.

The portable information terminal 7500 can receive a video signal with acontrol portion incorporated therein and can display the received videoon the display portion 7001. The portable information terminal 7500incorporates a battery. A terminal portion for connecting a connectormay be included in the housing 7501 so that a video signal or power canbe directly supplied from the outside with a wiring.

By pressing the operation buttons 7503, power on/off, switching ofdisplayed videos, and the like can be performed. Although FIGS. 28A1,28A2, and 28B illustrate an example where the operation buttons 7503 arepositioned on a side surface of the portable information terminal 7500,one embodiment of the present invention is not limited thereto. Theoperation buttons 7503 may be placed on a display surface (a frontsurface) or a rear surface of the portable information terminal 7500.

FIG. 28B illustrates the portable information terminal 7500 in a statewhere the display portion 7001 is pulled out. Videos can be displayed onthe display portion 7001 in this state. The display portion 7001 can beextracted by the display portion tab 7502. In addition, the portableinformation terminal 7500 may perform different displays in the statewhere part of the display portion 7001 is rolled as illustrated in FIG.28A1 and in the state where the display portion 7001 is pulled out asillustrated in FIG. 28B. For example, in the state illustrated in FIG.28A1, the rolled portion of the display portion 7001 is put in anon-display state, which results in a reduction in power consumption ofthe portable information terminal 7500.

Note that a reinforcement frame may be provided for a side portion ofthe display portion 7001 so that the display portion 7001 has a flatdisplay surface when pulled out.

Note that in addition to this structure, a speaker may be provided forthe housing so that sound is output with an audio signal receivedtogether with a video signal.

FIGS. 28C to 28E illustrate an example of a foldable portableinformation terminal. FIG. 28C illustrates a portable informationterminal 7600 that is opened. FIG. 28D illustrates the portableinformation terminal 7600 that is being opened or being folded. FIG. 28Eillustrates the portable information terminal 7600 that is folded. Theportable information terminal 7600 is highly portable when folded, andis highly browsable when opened because of a seamless large displayarea.

A display portion 7001 is supported by three housings 7601 joinedtogether by hinges 7602. By folding the portable information terminal7600 at a connection portion between two housings 7601 with the hinges7602, the portable information terminal 7600 can be reversibly changedin shape from an opened state to a folded state.

FIGS. 28F and 28G illustrate an example of a foldable portableinformation terminal. FIG. 28F illustrates a portable informationterminal 7650 that is folded so that the display portion 7001 is on theinside. FIG. 28G illustrates the portable information terminal 7650 thatis folded so that the display portion 7001 is on the outside. Theportable information terminal 7650 includes the display portion 7001 anda non-display portion 7651. When the portable information terminal 7650is not used, the portable information terminal 7650 is folded so thatthe display portion 7001 is on the inside, whereby the display portion7001 can be prevented from being contaminated or damaged.

FIG. 28H illustrates an example of a flexible portable informationterminal. The portable information terminal 7700 includes a housing 7701and the display portion 7001. In addition, the portable informationterminal 7700 may include buttons 7703 a and 7703 b which serve as inputmeans, speakers 7704 a and 7704 b which serve as sound output means, anexternal connection port 7705, a microphone 7706, or the like. Aflexible battery 7709 can be mounted on the portable informationterminal 7700. The battery 7709 may be arranged to overlap with thedisplay portion 7001, for example.

The housing 7701, the display portion 7001, the battery 7709 areflexible. Thus, it is easy to curve the portable information terminal7700 into a desired shape or to twist the portable information terminal7700. For example, the portable information terminal 7700 can be curvedso that the display portion 7001 is on the inside or in the outside. Theportable information terminal 7700 can be used in a rolled state. Sincethe housing 7701 and the display portion 7001 can be transformed freelyin this manner, the portable information terminal 7700 is less likely tobe broken even when the portable information terminal 7700 falls down orexternal stress is applied to the portable information terminal 7700.

The portable information terminal 7700 can be used effectively invarious situations because the portable information terminal 7700 islightweight. For example, the portable information terminal 7700 can beused in the state where the upper portion of the housing 7701 issuspended by a clip or the like, or in the state where the housing 7701is fixed to a wall by magnets or the like.

FIG. 28I illustrates an example of a wrist-watch-type portableinformation terminal. The portable information terminal 7800 includes aband 7801, the display portion 7001, an input-output terminal 7802,operation buttons 7803, or the like. The band 7801 has a function of ahousing. A flexible battery 7805 can be mounted on the portableinformation terminal 7800. The battery 7805 may overlap with the displayportion 7001 or the band 7801, for example.

The band 7801, the display portion 7001, and the battery 7805 haveflexibility. Thus, the portable information terminal 7800 can be easilycurved to have a desired shape.

With the operation button 7803, a variety of functions such as timesetting, on/off of the power, on/off of wireless communication, settingand cancellation of silent mode, and setting and cancellation of powersaving mode can be performed. For example, the functions of theoperation button 7803 can be set freely by the operating systemincorporated in the portable information terminal 7800.

By touching an icon 7804 displayed on the display portion 7001 with afinger or the like, application can be started.

The portable information terminal 7800 can employ near fieldcommunication that is a communication method based on an existingcommunication standard. In that case, for example, mutual communicationbetween the portable information terminal 7800 and a headset capable ofwireless communication can be performed, and thus hands-free calling ispossible.

The portable information terminal 7800 may include the input-outputterminal 7802. In the case where the input-output terminal 7802 isincluded, data can be directly transmitted to and received from anotherinformation terminal via a connector. Charging through the input-outputterminal 7802 is also possible. Note that charging of the portableinformation terminal described as an example in this embodiment can beperformed by non-contact power transmission without using theinput-output terminal.

This embodiment can be combined with any other embodiment asappropriate.

EXPLANATION OF REFERENCE

-   10: display system, 11: image processing device, 12: display device,    13: display region, 14: detection device, 15: pillar, 16: wall, 21:    decoder circuit, 22: signal dividing portion, 23 a: controller, 23    b: controller, 30 a: display panel, 30 b: display panel, 31 a:    driver circuit, 31 b: driver circuit, 51: arithmetic portion, 52:    memory portion, 92 a: region, 92 b: region, 92 c: region, 92 d:    region, 100: display panel, 100 a: display panel, 100 b: display    panel, 100 c: display panel, 100 d: display panel, 101: display    region, 101 a: display region, 101 b: display region, 101 c: display    region, 101 d: display region, 101 e: display region, 101 f: display    region, 102: region, 102 a: region, 102 b: region, 103:    light-transmitting layer, 103 a: light-transmitting layer, 103 b:    light-transmitting layer, 105 a: region, 105 b: region, 105 c:    region, 110: region, 110 a: region, 110 b: region, 110 c: region,    110 d: region, 112 a: FPC, 112 b: FPC, 120: region, 120 a: region,    120 b: region, 120 c: region, 123: FPC, 131: resin layer, 132:    protective substrate, 133: resin layer, 134: protective substrate,    141: pixel, 141 a: pixel, 141 b: pixel, 142 a: wiring, 142 b:    wiring, 143 a: circuit, 143 b: circuit, 145: wiring, 151: substrate,    151 a: substrate, 151 b: substrate, 152: substrate, 152 a:    substrate, 152 b: substrate, 153 a: element layer, 153 b: element    layer, 154: bonding layer, 155 a: region, 155 b: region, 156 a:    region, 156 b: region, 301: display portion, 302: pixel, 302B:    sub-pixel, 302G: sub-pixel, 302R: sub-pixel, 302 t: transistor, 303    c: capacitor, 303 g(1): scan line driver circuit, 303 g(2): imaging    pixel driver circuit, 303 s(1): image signal line driver circuit,    303 s(2): imaging signal line driver circuit, 303 t: transistor,    304: gate, 308: imaging pixel, 308 p: photoelectric conversion    element, 308 t: transistor, 309: FPC, 311: wiring, 319: terminal,    321: insulating layer, 328: partition, 329: spacer, 350R:    light-emitting element, 351R: lower electrode, 352: upper electrode,    353: EL layer, 353 a: EL layer, 353 b: EL layer, 354: intermediate    layer, 360: adhesive layer, 367B: coloring layer, 367BM:    light-blocking layer, 367G: coloring layer, 367 p: anti-reflective    layer, 367R: coloring layer, 390: touch panel, 500: display portion,    500TP: touch panel, 501: display portion, 503 g: driver circuit, 503    s: driver circuit, 505: touch panel, 505B: touch panel, 509: FPC,    590: substrate, 591: electrode, 592: electrode, 593: insulating    layer, 594: wiring, 595: touch sensor, 597: adhesive layer, 598:    wiring, 599: connection layer, 600: input portion, 602: sensing    unit, 603 d: driver circuit, 603 g: driver circuit, 650: capacitor,    651: electrode, 652: electrode, 653: insulating layer, 667: window    portion, 670: protective layer, 701: substrate, 703: adhesive layer,    705: insulating layer, 711: substrate, 713: adhesive layer, 715:    insulating layer, 804: light-emitting portion, 806: driver circuit    portion, 808: FPC, 814: conductive layer, 815: insulating layer,    817: insulating layer, 817 a: insulating layer, 817 b: insulating    layer, 820: transistor, 821: insulating layer, 822: adhesive layer,    823: spacer, 824: transistor, 825: connector, 830: light-emitting    element, 831: lower electrode, 832: optical adjustment layer, 833:    EL layer, 835: upper electrode, 845: coloring layer, 847:    light-blocking layer, 849: overcoat, 856: conductive layer, 857:    conductive layer, 857 a: conductive layer, 857 b: conductive layer,    7000: display portion, 7001: display portion, 7100: mobile phone,    7101: housing, 7103: operation button, 7104: external connection    port, 7105: speaker, 7106: microphone, 7200: television device,    7201: housing, 7203: stand, 7211: remote controller, 7300: portable    information terminal, 7301: housing, 7302: operation button, 7303:    data, 7400: lighting device, 7401: stage, 7402: light-emitting    portion, 7403: operation switch, 7500: portable information    terminal, 7501: housing, 7502: tab, 7503: operation button, 7600:    portable information terminal, 7601: housing, 7602: hinge, 7650:    portable information terminal, 7651: non-display portion, 7700:    portable information terminal, 7701: housing, 7703 a: button, 7703    b: button, 7704 a: speaker, 7704 b: speaker, 7705: external    connection port, 7706: microphone, 7709: battery, 7800: portable    information terminal, 7801: band, 7802: input-output terminal, 7803:    operation button, 7804: icon, and 7805: battery.

This application is based on Japanese Patent Application serial no.2014-241476 filed with Japan Patent Office on Nov. 28, 2014, the entirecontents of which are hereby incorporated by reference.

1. A display system comprising: a first display panel comprising a firstregion; a second display panel comprising a second region; and anarithmetic portion configured to produce a second image signal bycorrecting a first image signal on the basis of a correction data, andsupply the second image signal to the first display panel, wherein thefirst region is configured to display an image, wherein the secondregion is configured to transmit visible light, wherein the first regioncomprises a first portion overlapping with the second region, andwherein the second image signal is a signal in which gray scalecorresponding to the first portion is corrected, or a signal in whichgray scale corresponding to at least part of the first region excludingthe first portion is corrected.
 2. The display system according to claim1, wherein the second image signal is subjected to gamma correction. 3.The display system according to claim 1, wherein each of the firstdisplay panel and the second display panel has flexibility.
 4. Thedisplay system according to claim 1, further comprising alight-transmitting layer overlapping with the first portion of the firstregion, wherein the light-transmitting layer is provided between adisplay surface of the first display panel and an opposite surface of adisplay surface of the second display panel.
 5. The display systemaccording to claim 4, wherein the light-transmitting layer has a lighttransmittance of higher than or equal to 80% on average at a wavelengthlonger than or equal to 450 nm and shorter than or equal to 700 nm, andwherein the light-transmitting layer has a higher refractive index thanair.
 6. The display system according to claim 1, further comprises amemory portion configured to supply the correction data to thearithmetic portion.
 7. The display system according to claim 1, furthercomprising a detection device configured to acquire luminance data ofthe first display panel and the second display panel.
 8. An imageprocessing device comprising: an arithmetic portion configured toproduce a second image signal by correcting a first image signal on thebasis of a correction data, and supply the second image signal to adisplay device, wherein the display device comprises: a first displaypanel comprising a first region; and a second display panel comprising asecond region, wherein the first region is configured to display animage, wherein the second region is configured to transmit visiblelight, wherein the first region comprises a first portion overlappingwith the second region, and wherein the second image signal is a signalin which gray scale corresponding to the first portion is corrected, ora signal in which gray scale corresponding to at least part of the firstregion excluding the first portion is corrected.
 9. The image processingdevice according to claim 8, further comprising a memory portion,wherein the memory portion is configured to supply the correction datato the arithmetic portion.